diff --git a/.merlin b/.merlin
index 998a48f5..7cf051e1 100644
--- a/.merlin
+++ b/.merlin
@@ -4,6 +4,7 @@ S src/iter/
 S src/sexp/
 S src/threads/
 S src/string
+S src/monomorphic
 S benchs
 S examples
 S tests
@@ -19,3 +20,4 @@ PKG threads.posix
 PKG lwt
 PKG qcheck
 FLG -w +a-4-44-48-60@8
+FLG -open CCMonomorphic
diff --git a/_oasis b/_oasis
index fbf34b65..432d9828 100644
--- a/_oasis
+++ b/_oasis
@@ -44,20 +44,26 @@ Library "containers"
                     CCInt64, CCChar, CCResult, CCParse, CCArray_slice,
                     CCListLabels, CCArrayLabels, CCEqual,
                     Containers
-  BuildDepends:     bytes, result
+  BuildDepends:     bytes, result, containers.monomorphic
   # BuildDepends:     bytes, bisect_ppx
 
+Library "containers_monomorphic"
+  Path:             src/monomorphic
+  Modules:          CCMonomorphic
+  FindlibParent:    containers
+  FindlibName:      monomorphic
+
 Library "containers_unix"
   Path:             src/unix
   Modules:          CCUnix
-  BuildDepends:     bytes, result, unix
+  BuildDepends:     bytes, result, unix, containers.monomorphic
   FindlibParent:    containers
   FindlibName:      unix
 
 Library "containers_sexp"
   Path:             src/sexp
   Modules:          CCSexp, CCSexp_lex
-  BuildDepends:     bytes, result
+  BuildDepends:     bytes, result, containers.monomorphic
   FindlibParent:    containers
   FindlibName:      sexp
 
@@ -69,7 +75,7 @@ Library "containers_data"
                     CCMixset, CCGraph, CCHashSet, CCBitField,
                     CCHashTrie, CCWBTree, CCRAL, CCSimple_queue,
                     CCImmutArray, CCHet, CCZipper
-  BuildDepends:     bytes
+  BuildDepends:     bytes, containers.monomorphic
   # BuildDepends:     bytes, bisect_ppx
   FindlibParent:    containers
   FindlibName:      data
@@ -77,6 +83,7 @@ Library "containers_data"
 Library "containers_iter"
   Path:             src/iter
   Modules:          CCKTree, CCKList, CCLazy_list
+  BuildDepends:     containers.monomorphic
   FindlibParent:    containers
   FindlibName:      iter
 
@@ -120,6 +127,7 @@ Executable run_benchs
   MainIs:           run_benchs.ml
   BuildDepends:     containers, qcheck,
                     containers.data, containers.iter, containers.thread,
+                    containers.monomorphic,
                     sequence, gen, benchmark
 
 Executable run_bench_hash
diff --git a/_tags b/_tags
index 51eb014f..1f3db001 100644
--- a/_tags
+++ b/_tags
@@ -161,3 +161,4 @@ true: annot, bin_annot
 <src/**/*.ml> and not <src/misc/*.ml>: warn(+a-4-44-58-60@8)
 true: no_alias_deps, safe_string, short_paths, color(always)
 <src/**/*Labels.cm*>: nolabels
+not (<src/monomorphic/CCMonomorphic.*> or <qtest/*>): open(CCMonomorphic)
diff --git a/benchs/run_benchs.ml b/benchs/run_benchs.ml
index 8e10fc0d..4448b6a9 100644
--- a/benchs/run_benchs.ml
+++ b/benchs/run_benchs.ml
@@ -280,7 +280,7 @@ module Arr = struct
          let a2 = Array.copy a1 in
          sort_std a1;
          quicksort ~limit:10 a2;
-         assert (a1 = a2))
+         assert (CCArray.equal CCInt.equal a1 a2))
       [ 10; 100; 1000]
 
   let bench_sort ?(time=2) n =
@@ -366,16 +366,16 @@ module Cache = struct
 
   let bench_fib n =
     let l =
-      [ "replacing_fib (128)", make_fib (C.replacing 128), n
-      ; "LRU_fib (128)", make_fib (C.lru 128), n
-      ; "replacing_fib (16)", make_fib (C.replacing 16), n
-      ; "LRU_fib (16)", make_fib (C.lru 16), n
-      ; "unbounded", make_fib (C.unbounded 32), n
+      [ "replacing_fib (128)", make_fib (C.replacing ~eq:CCInt.equal 128), n
+      ; "LRU_fib (128)", make_fib (C.lru ~eq:CCInt.equal 128), n
+      ; "replacing_fib (16)", make_fib (C.replacing ~eq:CCInt.equal 16), n
+      ; "LRU_fib (16)", make_fib (C.lru ~eq:CCInt.equal 16), n
+      ; "unbounded", make_fib (C.unbounded ~eq:CCInt.equal 32), n
       ]
     in
     let l = if n <= 20
-      then  [ "linear_fib (5)", make_fib (C.linear 5), n
-            ; "linear_fib (32)", make_fib (C.linear 32), n
+      then  [ "linear_fib (5)", make_fib (C.linear ~eq:CCInt.equal 5), n
+            ; "linear_fib (32)", make_fib (C.linear ~eq:CCInt.equal 32), n
             ; "dummy_fib", make_fib C.dummy, n
             ] @ l
       else l
@@ -862,7 +862,7 @@ module Deque = struct
     let take_back d =
       match !d with
       | None -> raise Empty
-      | Some first when first == first.prev ->
+      | Some first when Pervasives.(==) first first.prev ->
         (* only one element *)
         d := None;
         first.content
@@ -875,7 +875,7 @@ module Deque = struct
     let take_front d =
       match !d with
       | None -> raise Empty
-      | Some first when first == first.prev ->
+      | Some first when Pervasives.(==) first first.prev ->
         (* only one element *)
         d := None;
         first.content
@@ -1045,7 +1045,7 @@ module Graph = struct
 
   let dfs_event n () =
     let tbl = CCGraph.mk_table ~eq:CCInt.equal ~hash:CCInt.hash (n+10) in
-    CCGraph.Traverse.Event.dfs ~tbl ~graph:div_graph_
+    CCGraph.Traverse.Event.dfs ~tbl ~eq:CCInt.equal ~graph:div_graph_
       (Sequence.return n)
     |> Sequence.fold
       (fun acc -> function
@@ -1154,7 +1154,7 @@ module Str = struct
     and mk_current () = CCString.find_all_l ~sub:needle haystack
     and mk_current_compiled =
       let f = CCString.find_all_l ~start:0 ~sub:needle in fun () -> f haystack in
-    assert (mk_naive () = mk_current ());
+    assert (CCList.equal CCInt.equal (mk_naive ()) (mk_current ()));
     B.throughputN 3 ~repeat
       [ "naive", mk_naive, ()
       ; "current", mk_current, ()
@@ -1168,7 +1168,7 @@ module Str = struct
     pp_pb needle haystack;
     let mk_naive () = find_all_l ~sub:needle haystack
     and mk_current () = CCString.find_all_l ~sub:needle haystack in
-    assert (mk_naive () = mk_current ());
+    assert (CCList.equal CCInt.equal (mk_naive ()) (mk_current ()));
     B.throughputN 3 ~repeat
       [ "naive", mk_naive, ()
       ; "current", mk_current, ()
@@ -1182,7 +1182,7 @@ module Str = struct
       let rec same s1 s2 i =
         if i = String.length s1 then true
         else (
-          String.unsafe_get s1 i = String.unsafe_get s2 i && same s1 s2 (i+1)
+          CCChar.equal (String.unsafe_get s1 i) (String.unsafe_get s2 i) && same s1 s2 (i+1)
         )
       in
       String.length pre <= String.length s &&
@@ -1193,7 +1193,7 @@ module Str = struct
       begin
         let i = ref 0 in
         while !i < String.length pre &&
-              String.unsafe_get s !i = String.unsafe_get pre !i
+              CCChar.equal (String.unsafe_get s !i) (String.unsafe_get pre !i)
         do incr i done;
         !i = String.length pre
       end
@@ -1225,7 +1225,7 @@ module Str = struct
       else
         let rec loop str p i =
           if i = len then true
-          else if String.unsafe_get str i <> String.unsafe_get p i then false
+          else if not (CCChar.equal (String.unsafe_get str i) (String.unsafe_get p i)) then false
           else loop str p (i + 1)
         in loop str p 0
 
@@ -1256,7 +1256,7 @@ module Str = struct
         Array.iteri
           (fun i (pre, y) ->
              let res = f ~pre y in
-             assert (res = output.(i)))
+             assert (CCBool.equal res output.(i)))
           input
       in
       Benchmark.throughputN 3
diff --git a/opam b/opam
index a82de59b..f930cfba 100644
--- a/opam
+++ b/opam
@@ -39,6 +39,6 @@ conflicts: [
 tags: [ "stdlib" "containers" "iterators" "list" "heap" "queue" ]
 homepage: "https://github.com/c-cube/ocaml-containers/"
 doc: "http://cedeela.fr/~simon/software/containers/"
-available: [ocaml-version >= "4.01.0"]
+available: [ocaml-version >= "4.02.0"]
 dev-repo: "https://github.com/c-cube/ocaml-containers.git"
 bug-reports: "https://github.com/c-cube/ocaml-containers/issues/"
diff --git a/src/core/CCArray.ml b/src/core/CCArray.ml
index 3daf1e7e..4fa0a86f 100644
--- a/src/core/CCArray.ml
+++ b/src/core/CCArray.ml
@@ -176,8 +176,7 @@ let sort_indices cmp a =
 *)
 
 let sort_ranking cmp a =
-  let cmp_int : int -> int -> int = Pervasives.compare in
-  sort_indices cmp_int (sort_indices cmp a)
+  sort_indices compare (sort_indices cmp a)
 
 (*$= & ~cmp:(=) ~printer:Q.Print.(array int)
   [||] (sort_ranking Pervasives.compare [||])
@@ -297,24 +296,24 @@ let _lookup_exn ~cmp k a i j =
         | n when n<0 -> _lookup_rec ~cmp k a (i+1) (j-1)
         | _ -> raise Not_found  (* too high *)
 
-let lookup_exn ?(cmp=Pervasives.compare) k a =
+let lookup_exn ~cmp k a =
   _lookup_exn ~cmp k a 0 (Array.length a-1)
 
-let lookup ?(cmp=Pervasives.compare) k a =
+let lookup ~cmp k a =
   try Some (_lookup_exn ~cmp k a 0 (Array.length a-1))
   with Not_found -> None
 
 (*$T
-  lookup 2 [|0;1;2;3;4;5|] = Some 2
-  lookup 4 [|0;1;2;3;4;5|] = Some 4
-  lookup 0 [|1;2;3;4;5|] = None
-  lookup 6 [|1;2;3;4;5|] = None
-  lookup 3 [| |] = None
-  lookup 1 [| 1 |] = Some 0
-  lookup 2 [| 1 |] = None
+  lookup ~cmp:CCInt.compare 2 [|0;1;2;3;4;5|] = Some 2
+  lookup ~cmp:CCInt.compare 4 [|0;1;2;3;4;5|] = Some 4
+  lookup ~cmp:CCInt.compare 0 [|1;2;3;4;5|] = None
+  lookup ~cmp:CCInt.compare 6 [|1;2;3;4;5|] = None
+  lookup ~cmp:CCInt.compare 3 [| |] = None
+  lookup ~cmp:CCInt.compare 1 [| 1 |] = Some 0
+  lookup ~cmp:CCInt.compare 2 [| 1 |] = None
 *)
 
-let bsearch ?(cmp=Pervasives.compare) k a =
+let bsearch ~cmp k a =
   let rec aux i j =
     if i > j
     then `Just_after j
@@ -333,13 +332,13 @@ let bsearch ?(cmp=Pervasives.compare) k a =
     | _ -> aux 0 (n-1)
 
 (*$T bsearch
-  bsearch 3 [|1; 2; 2; 3; 4; 10|] = `At 3
-  bsearch 5 [|1; 2; 2; 3; 4; 10|] = `Just_after 4
-  bsearch 1 [|1; 2; 5; 5; 11; 12|] = `At 0
-  bsearch 12 [|1; 2; 5; 5; 11; 12|] = `At 5
-  bsearch 10 [|1; 2; 2; 3; 4; 9|] = `All_lower
-  bsearch 0 [|1; 2; 2; 3; 4; 9|] = `All_bigger
-  bsearch 3 [| |] = `Empty
+  bsearch ~cmp:CCInt.compare 3 [|1; 2; 2; 3; 4; 10|] = `At 3
+  bsearch ~cmp:CCInt.compare 5 [|1; 2; 2; 3; 4; 10|] = `Just_after 4
+  bsearch ~cmp:CCInt.compare 1 [|1; 2; 5; 5; 11; 12|] = `At 0
+  bsearch ~cmp:CCInt.compare 12 [|1; 2; 5; 5; 11; 12|] = `At 5
+  bsearch ~cmp:CCInt.compare 10 [|1; 2; 2; 3; 4; 9|] = `All_lower
+  bsearch ~cmp:CCInt.compare 0 [|1; 2; 2; 3; 4; 9|] = `All_bigger
+  bsearch ~cmp:CCInt.compare 3 [| |] = `Empty
 *)
 
 let (>>=) a f = flat_map f a
@@ -664,7 +663,7 @@ end
 
 let sort_generic (type arr)(type elt)
     (module A : MONO_ARRAY with type t = arr and type elt = elt)
-    ?(cmp=Pervasives.compare) a
+    ~cmp a
   =
   let module S = SortGeneric(A) in
   S.sort ~cmp a
diff --git a/src/core/CCArray.mli b/src/core/CCArray.mli
index c0a99efe..d6da8cde 100644
--- a/src/core/CCArray.mli
+++ b/src/core/CCArray.mli
@@ -119,18 +119,18 @@ val find_idx : ('a -> bool) -> 'a t -> (int * 'a) option
     and [p x] holds. Otherwise returns [None]
     @since 0.3.4 *)
 
-val lookup : ?cmp:'a ord -> 'a -> 'a t -> int option
+val lookup : cmp:'a ord -> 'a -> 'a t -> int option
 (** Lookup the index of some value in a sorted array.
     Undefined behavior if the array is not sorted wrt [cmp].
     Complexity: [O(log (n))] (dichotomic search).
     @return [None] if the key is not present, or
       [Some i] ([i] the index of the key) otherwise *)
 
-val lookup_exn : ?cmp:'a ord -> 'a -> 'a t -> int
+val lookup_exn : cmp:'a ord -> 'a -> 'a t -> int
 (** Same as {!lookup}, but
     @raise Not_found if the key is not present *)
 
-val bsearch : ?cmp:('a -> 'a -> int) -> 'a -> 'a t ->
+val bsearch : cmp:('a -> 'a -> int) -> 'a -> 'a t ->
   [ `All_lower | `All_bigger | `Just_after of int | `Empty | `At of int ]
 (** [bsearch ?cmp x arr] finds the index of the object [x] in the array [arr],
     provided [arr] is {b sorted} using [cmp]. If the array is not sorted,
@@ -256,7 +256,7 @@ end
 
 val sort_generic :
   (module MONO_ARRAY with type t = 'arr and type elt = 'elt) ->
-  ?cmp:('elt -> 'elt -> int) -> 'arr -> unit
+  cmp:('elt -> 'elt -> int) -> 'arr -> unit
 (** Sort the array, without allocating (eats stack space though). Performance
     might be lower than {!Array.sort}.
     @since 0.14 *)
diff --git a/src/core/CCArrayLabels.mli b/src/core/CCArrayLabels.mli
index fdf3784b..e2d5afa0 100644
--- a/src/core/CCArrayLabels.mli
+++ b/src/core/CCArrayLabels.mli
@@ -90,16 +90,16 @@ val find_idx : f:('a -> bool) -> 'a t -> (int * 'a) option
     and [p x] holds. Otherwise returns [None]
     @since 0.3.4 *)
 
-val lookup : ?cmp:'a ord -> key:'a -> 'a t -> int option
+val lookup : cmp:'a ord -> key:'a -> 'a t -> int option
 (** Lookup the index of some value in a sorted array.
     @return [None] if the key is not present, or
       [Some i] ([i] the index of the key) otherwise *)
 
-val lookup_exn : ?cmp:'a ord -> key:'a -> 'a t -> int
+val lookup_exn : cmp:'a ord -> key:'a -> 'a t -> int
 (** Same as {!lookup_exn}, but
     @raise Not_found if the key is not present *)
 
-val bsearch : ?cmp:('a -> 'a -> int) -> key:'a -> 'a t ->
+val bsearch : cmp:('a -> 'a -> int) -> key:'a -> 'a t ->
   [ `All_lower | `All_bigger | `Just_after of int | `Empty | `At of int ]
 (** [bsearch ?cmp key arr] finds the index of the object [key] in the array [arr],
     provided [arr] is {b sorted} using [cmp]. If the array is not sorted,
@@ -225,7 +225,7 @@ end
 
 val sort_generic :
   (module MONO_ARRAY with type t = 'arr and type elt = 'elt) ->
-  ?cmp:('elt -> 'elt -> int) -> 'arr -> unit
+  cmp:('elt -> 'elt -> int) -> 'arr -> unit
 (** Sort the array, without allocating (eats stack space though). Performance
     might be lower than {!Array.sort}.
     @since 0.14 *)
diff --git a/src/core/CCArray_slice.ml b/src/core/CCArray_slice.ml
index fcbe1204..9e96841b 100644
--- a/src/core/CCArray_slice.ml
+++ b/src/core/CCArray_slice.ml
@@ -85,6 +85,7 @@ let rec _compare cmp a1 i1 j1 a2 i2 j2 =
 let equal eq a b =
   length a = length b && _equal eq a.arr a.i a.j b.arr b.i b.j
 
+let compare_int (a : int) b = Pervasives.compare a b
 let compare cmp a b =
   _compare cmp a.arr a.i a.j b.arr b.i b.j
 
@@ -292,9 +293,8 @@ let sorted cmp a = _sorted cmp a.arr a.i a.j
 
 let sort_ranking cmp a =
   let idx = _sort_indices cmp a.arr a.i a.j in
-  let cmp_int : int -> int -> int = Pervasives.compare in
   let sort_indices cmp a = _sort_indices cmp a 0 (Array.length a) in
-  sort_indices cmp_int idx
+  sort_indices compare_int idx
 
 (*$= & ~cmp:(=) ~printer:Q.Print.(array int)
   [||] \
@@ -345,18 +345,18 @@ let find_idx p a =
   (Some (1,"c")) (find_idx ((=) "c") (make [| "a"; "b"; "c" |] 1 2))
 *)
 
-let lookup_exn ?(cmp=Pervasives.compare) k a =
+let lookup_exn ~cmp k a =
   _lookup_exn ~cmp k a.arr a.i (a.j-1) - a.i
 
-let lookup ?(cmp=Pervasives.compare) k a =
+let lookup ~cmp k a =
   try Some (_lookup_exn ~cmp k a.arr a.i (a.j-1) - a.i)
   with Not_found -> None
 
 (*$=
-  (Some 1) (lookup "c" (make [| "a"; "b"; "c" |] 1 2))
+  (Some 1) (lookup ~cmp:CCString.compare "c" (make [| "a"; "b"; "c" |] 1 2))
 *)
 
-let bsearch ?(cmp=Pervasives.compare) k a =
+let bsearch ~cmp k a =
   match bsearch_ ~cmp k a.arr a.i (a.j - 1) with
     | `At m -> `At (m - a.i)
     | `Just_after m -> `Just_after (m - a.i)
diff --git a/src/core/CCArray_slice.mli b/src/core/CCArray_slice.mli
index 1a5989bc..e72dd00f 100644
--- a/src/core/CCArray_slice.mli
+++ b/src/core/CCArray_slice.mli
@@ -86,10 +86,10 @@ val sorted : ('a -> 'a -> int) -> 'a t -> 'a array
 
 val sort_indices : ('a -> 'a -> int) -> 'a t -> int array
 (** [sort_indices cmp a] returns a new array [b], with the same length as [a],
-    such that [b.(i)] is the index at which the [i]-th element of [sorted cmp a] 
+    such that [b.(i)] is the index at which the [i]-th element of [sorted cmp a]
     appears in [a]. [a] is not modified.
 
-    In other words, [map (fun i -> a.(i)) (sort_indices cmp a) = sorted cmp a]. 
+    In other words, [map (fun i -> a.(i)) (sort_indices cmp a) = sorted cmp a].
     [sort_indices] yields the inverse permutation of {!sort_ranking}.
 
     @since 1.0 *)
@@ -99,7 +99,7 @@ val sort_ranking : ('a -> 'a -> int) -> 'a t -> int array
     such that [b.(i)] is the index at which the [i]-the element of [a] appears
     in [sorted cmp a]. [a] is not modified.
 
-    In other words, [map (fun i -> (sorted cmp a).(i)) (sort_ranking cmp a) = a]. 
+    In other words, [map (fun i -> (sorted cmp a).(i)) (sort_ranking cmp a) = a].
     [sort_ranking] yields the inverse permutation of {!sort_indices}.
 
     In the absence of duplicate elements in [a], we also have
@@ -119,16 +119,16 @@ val find_idx : ('a -> bool) -> 'a t -> (int * 'a) option
     and [p x] holds. Otherwise returns [None]
     @since 0.3.4 *)
 
-val lookup : ?cmp:'a ord -> 'a -> 'a t -> int option
+val lookup : cmp:'a ord -> 'a -> 'a t -> int option
 (** Lookup the index of some value in a sorted array.
     @return [None] if the key is not present, or
       [Some i] ([i] the index of the key) otherwise *)
 
-val lookup_exn : ?cmp:'a ord -> 'a -> 'a t -> int
+val lookup_exn : cmp:'a ord -> 'a -> 'a t -> int
 (** Same as {!lookup}, but
     @raise Not_found if the key is not present *)
 
-val bsearch : ?cmp:('a -> 'a -> int) -> 'a -> 'a t ->
+val bsearch : cmp:('a -> 'a -> int) -> 'a -> 'a t ->
   [ `All_lower | `All_bigger | `Just_after of int | `Empty | `At of int ]
 (** [bsearch ?cmp x arr] finds the index of the object [x] in the array [arr],
     provided [arr] is {b sorted} using [cmp]. If the array is not sorted,
diff --git a/src/core/CCBool.ml b/src/core/CCBool.ml
index 087d0101..89a6a9e5 100644
--- a/src/core/CCBool.ml
+++ b/src/core/CCBool.ml
@@ -3,7 +3,7 @@
 
 type t = bool
 
-let equal (a:bool) b = a=b
+let equal (a:bool) b = Pervasives.(=) a b
 
 let compare (a:bool) b = Pervasives.compare a b
 
diff --git a/src/core/CCChar.ml b/src/core/CCChar.ml
index 55900bd6..68d45cad 100644
--- a/src/core/CCChar.ml
+++ b/src/core/CCChar.ml
@@ -6,7 +6,7 @@
 
 include Char
 
-let equal (a:char) b = a=b
+let equal (a:char) b = Pervasives.(=) a b
 
 let pp = Buffer.add_char
 let print = Format.pp_print_char
@@ -15,12 +15,10 @@ let of_int_exn = Char.chr
 let of_int c = try Some (of_int_exn c) with _ -> None
 let to_int = Char.code
 
-let lowercase_ascii c =
-  if c >= 'A' && c <= 'Z'
-  then Char.unsafe_chr (Char. code c + 32)
-  else c
+let lowercase_ascii = function
+  | 'A'..'Z' as c -> Char.unsafe_chr (Char.code c + 32)
+  | c -> c
 
-let uppercase_ascii c =
-  if c >= 'a' && c <= 'z'
-  then Char.unsafe_chr (Char.code c - 32)
-  else c
+let uppercase_ascii = function
+  | 'a'..'z' as c -> Char.unsafe_chr (Char.code c - 32)
+  | c -> c
diff --git a/src/core/CCEqual.ml b/src/core/CCEqual.ml
index f879bd05..13ee4d79 100644
--- a/src/core/CCEqual.ml
+++ b/src/core/CCEqual.ml
@@ -5,12 +5,13 @@
 
 type 'a t = 'a -> 'a -> bool
 
-let poly = (=)
+let poly = Pervasives.(=)
+let physical = Pervasives.(==)
 
 let int : int t = (=)
-let string : string t = (=)
-let bool : bool t = (=)
-let float : float t = (=)
+let string : string t = Pervasives.(=)
+let bool : bool t = Pervasives.(=)
+let float : float t = Pervasives.(=)
 let unit () () = true
 
 let rec list f l1 l2 = match l1, l2 with
diff --git a/src/core/CCEqual.mli b/src/core/CCEqual.mli
index 94230bfa..efcbc3ea 100644
--- a/src/core/CCEqual.mli
+++ b/src/core/CCEqual.mli
@@ -11,6 +11,10 @@ type 'a t = 'a -> 'a -> bool
 val poly : 'a t
 (** Standard polymorphic equality *)
 
+val physical : 'a t
+(** Standard physical equality
+    @since NEXT_RELEASE *)
+
 val int : int t
 val string : string t
 val bool : bool t
diff --git a/src/core/CCFloat.ml b/src/core/CCFloat.ml
index 2e7fcc41..cb4062b9 100644
--- a/src/core/CCFloat.ml
+++ b/src/core/CCFloat.ml
@@ -9,6 +9,16 @@ type fpclass = Pervasives.fpclass =
   | FP_infinite
   | FP_nan
 
+module Infix = struct
+  let (=) = Pervasives.(=)
+  let (<>) = Pervasives.(<>)
+  let (<) = Pervasives.(<)
+  let (>) = Pervasives.(>)
+  let (<=) = Pervasives.(<=)
+  let (>=) = Pervasives.(>=)
+end
+include Infix
+
 let nan = Pervasives.nan
 
 let infinity = Pervasives.infinity
@@ -84,13 +94,3 @@ let random_range i j st = i +. random (j-.i) st
 let equal_precision ~epsilon a b = abs_float (a-.b) < epsilon
 
 let classify = Pervasives.classify_float
-
-module Infix = struct
-  let (=) = Pervasives.(=)
-  let (<>) = Pervasives.(<>)
-  let (<) = Pervasives.(<)
-  let (>) = Pervasives.(>)
-  let (<=) = Pervasives.(<=)
-  let (>=) = Pervasives.(>=)
-end
-include Infix
diff --git a/src/core/CCInt.ml b/src/core/CCInt.ml
index eb37fccc..cc87f080 100644
--- a/src/core/CCInt.ml
+++ b/src/core/CCInt.ml
@@ -5,7 +5,7 @@ type t = int
 
 let equal (a:int) b = a=b
 
-let compare (a:int) b = Pervasives.compare a b
+let compare a b = compare a b
 
 let hash i = i land max_int
 
@@ -75,9 +75,11 @@ let floor_div a n =
       (fun (n, m) -> floor_div n (-m) = int_of_float @@ floor (float n /. float (-m)))
 *)
 
+let bool_neq (a : bool) b = Pervasives.(<>) a b
+
 let rem a n =
   let y = a mod n in
-  if (y < 0) <> (n < 0) && y <> 0 then
+  if bool_neq (y < 0) (n < 0) && y <> 0 then
     y + n
   else
     y
@@ -245,12 +247,12 @@ let range' i j yield =
 
 
 module Infix = struct
-  let (=) = Pervasives.(=)
-  let (<>) = Pervasives.(<>)
-  let (<) = Pervasives.(<)
-  let (>) = Pervasives.(>)
-  let (<=) = Pervasives.(<=)
-  let (>=) = Pervasives.(>=)
+  let (=) = (=)
+  let (<>) = (<>)
+  let (<) = (<)
+  let (>) = (>)
+  let (<=) = (<=)
+  let (>=) = (>=)
   let (--) = range
   let (--^) = range'
 end
diff --git a/src/core/CCInt64.ml b/src/core/CCInt64.ml
index f9ab3841..9ac33506 100644
--- a/src/core/CCInt64.ml
+++ b/src/core/CCInt64.ml
@@ -28,7 +28,7 @@ let (lsr) = shift_right_logical
 
 let (asr) = shift_right
 
-let equal (x:t) y = x=y
+let equal (x:t) y = Pervasives.(=) x y
 
 let hash x = Pervasives.abs (to_int x)
 
diff --git a/src/core/CCList.ml b/src/core/CCList.ml
index 601fb06d..ec33ae71 100644
--- a/src/core/CCList.ml
+++ b/src/core/CCList.ml
@@ -557,7 +557,7 @@ let map_product_l f l =
     cmp_lii_unord (cartesian_product l) (map_product_l CCFun.id l))
 *)
 
-let sorted_merge ?(cmp=Pervasives.compare) l1 l2 =
+let sorted_merge ~cmp l1 l2 =
   let rec recurse cmp acc l1 l2 = match l1,l2 with
     | [], _ -> List.rev_append acc l2
     | _, [] -> List.rev_append acc l1
@@ -572,15 +572,15 @@ let sorted_merge ?(cmp=Pervasives.compare) l1 l2 =
 (*$T
   List.sort Pervasives.compare ([(( * )2); ((+)1)] <*> [10;100]) \
     = [11; 20; 101; 200]
-  sorted_merge [1;1;2] [1;2;3] = [1;1;1;2;2;3]
+  sorted_merge ~cmp:CCInt.compare [1;1;2] [1;2;3] = [1;1;1;2;2;3]
 *)
 
 (*$Q
   Q.(pair (list int) (list int)) (fun (l1,l2) -> \
-    List.length (sorted_merge l1 l2) = List.length l1 + List.length l2)
+    List.length (sorted_merge ~cmp:CCInt.compare l1 l2) = List.length l1 + List.length l2)
 *)
 
-let sort_uniq (type elt) ?(cmp=Pervasives.compare) l =
+let sort_uniq (type elt) ~cmp l =
   let module S = Set.Make(struct
       type t = elt
       let compare = cmp
@@ -589,12 +589,12 @@ let sort_uniq (type elt) ?(cmp=Pervasives.compare) l =
   S.elements set
 
 (*$T
-  sort_uniq [1;2;5;3;6;1;4;2;3] = [1;2;3;4;5;6]
-  sort_uniq [] = []
-  sort_uniq [10;10;10;10;1;10] = [1;10]
+  sort_uniq ~cmp:CCInt.compare [1;2;5;3;6;1;4;2;3] = [1;2;3;4;5;6]
+  sort_uniq ~cmp:CCInt.compare [] = []
+  sort_uniq ~cmp:CCInt.compare [10;10;10;10;1;10] = [1;10]
 *)
 
-let is_sorted ?(cmp=Pervasives.compare) l =
+let is_sorted ~cmp l =
   let rec aux cmp = function
     | [] | [_] -> true
     | x :: ((y :: _) as tail) -> cmp x y <= 0 && aux cmp tail
@@ -603,10 +603,10 @@ let is_sorted ?(cmp=Pervasives.compare) l =
 
 (*$Q
   Q.(list small_int) (fun l -> \
-    is_sorted (List.sort Pervasives.compare l))
+    is_sorted ~cmp:CCInt.compare (List.sort Pervasives.compare l))
 *)
 
-let sorted_insert ?(cmp=Pervasives.compare) ?(uniq=false) x l =
+let sorted_insert ~cmp ?(uniq=false) x l =
   let rec aux cmp uniq x left l = match l with
     | [] -> List.rev_append left [x]
     | y :: tail ->
@@ -622,20 +622,20 @@ let sorted_insert ?(cmp=Pervasives.compare) ?(uniq=false) x l =
 (*$Q
     Q.(pair small_int (list small_int)) (fun (x,l) -> \
       let l = List.sort Pervasives.compare l in \
-      is_sorted (sorted_insert ~uniq:true x l))
+      is_sorted ~cmp:CCInt.compare (sorted_insert ~cmp:CCInt.compare ~uniq:true x l))
     Q.(pair small_int (list small_int)) (fun (x,l) -> \
       let l = List.sort Pervasives.compare l in \
-      is_sorted (sorted_insert ~uniq:false x l))
+      is_sorted ~cmp:CCInt.compare (sorted_insert ~cmp:CCInt.compare ~uniq:false x l))
     Q.(pair small_int (list small_int)) (fun (x,l) -> \
       let l = List.sort Pervasives.compare l in \
-      let l' = sorted_insert ~uniq:false x l in \
+      let l' = sorted_insert ~cmp:CCInt.compare ~uniq:false x l in \
       List.length l' = List.length l + 1)
     Q.(pair small_int (list small_int)) (fun (x,l) -> \
       let l = List.sort Pervasives.compare l in \
-      List.mem x (sorted_insert x l))
+      List.mem x (sorted_insert ~cmp:CCInt.compare x l))
 *)
 
-let uniq_succ ?(eq=(=)) l =
+let uniq_succ ~eq l =
   let rec f acc l = match l with
     | [] -> List.rev acc
     | [x] -> List.rev (x::acc)
@@ -645,10 +645,10 @@ let uniq_succ ?(eq=(=)) l =
   f [] l
 
 (*$T
-  uniq_succ [1;1;2;3;1;6;6;4;6;1] = [1;2;3;1;6;4;6;1]
+  uniq_succ ~eq:CCInt.equal [1;1;2;3;1;6;6;4;6;1] = [1;2;3;1;6;4;6;1]
 *)
 
-let group_succ ?(eq=(=)) l =
+let group_succ ~eq l =
   let rec f ~eq acc cur l = match cur, l with
     | [], [] -> List.rev acc
     | _::_, [] -> List.rev (List.rev cur :: acc)
@@ -659,15 +659,15 @@ let group_succ ?(eq=(=)) l =
   f ~eq [] [] l
 
 (*$T
-  group_succ [1;2;3;1;1;2;4] = [[1]; [2]; [3]; [1;1]; [2]; [4]]
-  group_succ [] = []
-  group_succ [1;1;1] = [[1;1;1]]
-  group_succ [1;2;2;2] = [[1]; [2;2;2]]
+  group_succ ~eq:CCInt.equal [1;2;3;1;1;2;4] = [[1]; [2]; [3]; [1;1]; [2]; [4]]
+  group_succ ~eq:CCInt.equal [] = []
+  group_succ ~eq:CCInt.equal [1;1;1] = [[1;1;1]]
+  group_succ ~eq:CCInt.equal [1;2;2;2] = [[1]; [2;2;2]]
   group_succ ~eq:(fun (x,_)(y,_)-> x=y) [1, 1; 1, 2; 1, 3; 2, 0] \
     = [[1, 1; 1, 2; 1, 3]; [2, 0]]
 *)
 
-let sorted_merge_uniq ?(cmp=Pervasives.compare) l1 l2 =
+let sorted_merge_uniq ~cmp l1 l2 =
   let push ~cmp acc x = match acc with
     | [] -> [x]
     | y :: _ when cmp x y > 0 -> x :: acc
@@ -687,21 +687,21 @@ let sorted_merge_uniq ?(cmp=Pervasives.compare) l1 l2 =
   recurse ~cmp [] l1 l2
 
 (*$T
-  sorted_merge_uniq [1; 1; 2; 3; 5; 8] [1; 2; 3; 4; 6; 8; 9; 9] = [1;2;3;4;5;6;8;9]
+  sorted_merge_uniq ~cmp:CCInt.compare [1; 1; 2; 3; 5; 8] [1; 2; 3; 4; 6; 8; 9; 9] = [1;2;3;4;5;6;8;9]
 *)
 
 (*$Q
   Q.(list int) (fun l -> \
     let l = List.sort Pervasives.compare l in \
-    sorted_merge_uniq l [] = uniq_succ l)
+    sorted_merge_uniq ~cmp:CCInt.compare l [] = uniq_succ ~eq:CCInt.equal l)
   Q.(list int) (fun l -> \
     let l = List.sort Pervasives.compare l in \
-    sorted_merge_uniq [] l = uniq_succ l)
+    sorted_merge_uniq ~cmp:CCInt.compare [] l = uniq_succ ~eq:CCInt.equal l)
   Q.(pair (list int) (list int)) (fun (l1, l2) -> \
     let l1 = List.sort Pervasives.compare l1 \
     and l2 = List.sort Pervasives.compare l2 in \
-    let l3 = sorted_merge_uniq l1 l2 in \
-    uniq_succ l3 = l3)
+    let l3 = sorted_merge_uniq ~cmp:CCInt.compare l1 l2 in \
+    uniq_succ ~eq:CCInt.equal l3 = l3)
 *)
 
 let take n l =
@@ -766,7 +766,7 @@ let sublists_of_len ?(last=fun _ -> None) ?offset n l =
   (* add sub-lists of [l] to [acc] *)
   let rec aux acc l =
     let group = take n l in
-    if group=[] then acc (* this was the last group, we are done *)
+    if is_empty group then acc (* this was the last group, we are done *)
     else if List.length group < n (* last group, with missing elements *)
     then match last group with
       | None -> acc
@@ -900,7 +900,7 @@ let find_idx p l = find_mapi (fun i x -> if p x then Some (i, x) else None) l
   find_map (fun x -> if x=3 then Some "a" else None) [1;2;4;5] = None
 *)
 
-let remove ?(eq=(=)) ~x l =
+let remove ~eq ~x l =
   let rec remove' eq x acc l = match l with
     | [] -> List.rev acc
     | y :: tail when eq x y -> remove' eq x acc tail
@@ -909,8 +909,8 @@ let remove ?(eq=(=)) ~x l =
   remove' eq x [] l
 
 (*$T
-  remove ~x:1 [2;1;3;3;2;1] = [2;3;3;2]
-  remove ~x:10 [1;2;3] = [1;2;3]
+  remove ~eq:CCInt.equal ~x:1 [2;1;3;3;2;1] = [2;3;3;2]
+  remove ~eq:CCInt.equal ~x:10 [1;2;3] = [1;2;3]
 *)
 
 let filter_map f l =
@@ -972,16 +972,16 @@ let all_ok l =
   (Error "e2") (all_ok [Ok 1; Error "e2"; Error "e3"; Ok 4])
 *)
 
-let mem ?(eq=(=)) x l =
+let mem ~eq x l =
   let rec search eq x l = match l with
     | [] -> false
     | y::l' -> eq x y || search eq x l'
   in search eq x l
 
-let add_nodup ?(eq=(=)) x l =
+let add_nodup ~eq x l =
   if mem ~eq x l then l else x::l
 
-let remove_one ?(eq=(=)) x l =
+let remove_one ~eq x l =
   let rec remove_one ~eq x acc l = match l with
     | [] -> assert false
     | y :: tl when eq x y -> List.rev_append acc tl
@@ -991,19 +991,19 @@ let remove_one ?(eq=(=)) x l =
 
 (*$Q
   Q.(pair int (list int)) (fun (x,l) -> \
-    remove_one x (add_nodup x l) = l)
+    remove_one ~eq:CCInt.equal x (add_nodup ~eq:CCInt.equal x l) = l)
   Q.(pair int (list int)) (fun (x,l) -> \
-    mem x l || List.length (add_nodup x l) = List.length l + 1)
+    mem ~eq:CCInt.equal x l || List.length (add_nodup ~eq:CCInt.equal x l) = List.length l + 1)
   Q.(pair int (list int)) (fun (x,l) -> \
-    not (mem x l) || List.length (remove_one x l) = List.length l - 1)
+    not (mem ~eq:CCInt.equal x l) || List.length (remove_one ~eq:CCInt.equal x l) = List.length l - 1)
 *)
 
-let subset ?(eq=(=)) l1 l2 =
+let subset ~eq l1 l2 =
   List.for_all
     (fun t -> mem ~eq t l2)
     l1
 
-let uniq ?(eq=(=)) l =
+let uniq ~eq l =
   let rec uniq eq acc l = match l with
     | [] -> List.rev acc
     | x::xs when List.exists (eq x) xs -> uniq eq acc xs
@@ -1011,15 +1011,15 @@ let uniq ?(eq=(=)) l =
   in uniq eq [] l
 
 (*$T
-  uniq [1;1;2;2;3;4;4;2;4;1;5] |> List.sort Pervasives.compare = [1;2;3;4;5]
+  uniq ~eq:CCInt.equal [1;1;2;2;3;4;4;2;4;1;5] |> List.sort Pervasives.compare = [1;2;3;4;5]
 *)
 
 (*$Q
   Q.(small_list small_int) (fun l -> \
-    sort_uniq l = (uniq l |> sort Pervasives.compare))
+    sort_uniq ~cmp:CCInt.compare l = (uniq ~eq:CCInt.equal l |> sort Pervasives.compare))
   *)
 
-let union ?(eq=(=)) l1 l2 =
+let union ~eq l1 l2 =
   let rec union eq acc l1 l2 = match l1 with
     | [] -> List.rev_append acc l2
     | x::xs when mem ~eq x l2 -> union eq acc xs l2
@@ -1027,10 +1027,10 @@ let union ?(eq=(=)) l1 l2 =
   in union eq [] l1 l2
 
 (*$T
-  union [1;2;4] [2;3;4;5] = [1;2;3;4;5]
+  union ~eq:CCInt.equal [1;2;4] [2;3;4;5] = [1;2;3;4;5]
 *)
 
-let inter ?(eq=(=)) l1 l2 =
+let inter ~eq l1 l2 =
   let rec inter eq acc l1 l2 = match l1 with
     | [] -> List.rev acc
     | x::xs when mem ~eq x l2 -> inter eq (x::acc) xs l2
@@ -1038,7 +1038,7 @@ let inter ?(eq=(=)) l1 l2 =
   in inter eq [] l1 l2
 
 (*$T
-  inter [1;2;4] [2;3;4;5] = [2;4]
+  inter ~eq:CCInt.equal [1;2;4] [2;3;4;5] = [2;4]
 *)
 
 let mapi f l =
@@ -1236,17 +1236,17 @@ module Assoc = struct
     | (y,z)::l' ->
       if eq x y then z else search_exn eq l' x
 
-  let get_exn ?(eq=(=)) x l = search_exn eq l x
+  let get_exn ~eq x l = search_exn eq l x
 
-  let get ?(eq=(=)) x l =
+  let get ~eq x l =
     try Some (search_exn eq l x)
     with Not_found -> None
 
   (*$T
-    Assoc.get 1 [1, "1"; 2, "2"] = Some "1"
-    Assoc.get 2 [1, "1"; 2, "2"] = Some "2"
-    Assoc.get 3 [1, "1"; 2, "2"] = None
-    Assoc.get 42 [] = None
+    Assoc.get ~eq:CCInt.equal 1 [1, "1"; 2, "2"] = Some "1"
+    Assoc.get ~eq:CCInt.equal 2 [1, "1"; 2, "2"] = Some "2"
+    Assoc.get ~eq:CCInt.equal 3 [1, "1"; 2, "2"] = None
+    Assoc.get ~eq:CCInt.equal 42 [] = None
   *)
 
   (* search for a binding for [x] in [l], and calls [f x (Some v) rest]
@@ -1259,27 +1259,27 @@ module Assoc = struct
       then f x (Some y') (List.rev_append acc l')
       else search_set eq ((x',y')::acc) l' x ~f
 
-  let set ?(eq=(=)) x y l =
+  let set ~eq x y l =
     search_set eq [] l x
       ~f:(fun x _ l -> (x,y)::l)
 
   (*$T
-    Assoc.set 2 "two" [1,"1"; 2, "2"] |> List.sort Pervasives.compare \
+    Assoc.set ~eq:CCInt.equal 2 "two" [1,"1"; 2, "2"] |> List.sort Pervasives.compare \
       = [1, "1"; 2, "two"]
-    Assoc.set 3 "3" [1,"1"; 2, "2"] |> List.sort Pervasives.compare \
+    Assoc.set ~eq:CCInt.equal 3 "3" [1,"1"; 2, "2"] |> List.sort Pervasives.compare \
       = [1, "1"; 2, "2"; 3, "3"]
   *)
 
-  let mem ?(eq=(=)) x l =
+  let mem ~eq x l =
     try ignore (search_exn eq l x); true
     with Not_found -> false
 
   (*$T
-    Assoc.mem 1 [1,"1"; 2,"2"; 3, "3"]
-    not (Assoc.mem 4 [1,"1"; 2,"2"; 3, "3"])
+    Assoc.mem ~eq:CCInt.equal 1 [1,"1"; 2,"2"; 3, "3"]
+    not (Assoc.mem ~eq:CCInt.equal 4 [1,"1"; 2,"2"; 3, "3"])
   *)
 
-  let update ?(eq=(=)) ~f x l =
+  let update ~eq ~f x l =
     search_set eq [] l x
       ~f:(fun x opt_y rest ->
         match f opt_y with
@@ -1287,17 +1287,17 @@ module Assoc = struct
           | Some y' -> (x,y') :: rest)
   (*$=
     [1,"1"; 2,"22"] \
-      (Assoc.update 2 [1,"1"; 2,"2"] \
+      (Assoc.update ~eq:CCInt.equal 2 [1,"1"; 2,"2"] \
         ~f:(function Some "2" -> Some "22" | _ -> assert false) |> lsort)
     [1,"1"; 3,"3"] \
-      (Assoc.update 2 [1,"1"; 2,"2"; 3,"3"] \
+      (Assoc.update ~eq:CCInt.equal 2 [1,"1"; 2,"2"; 3,"3"] \
         ~f:(function Some "2" -> None | _ -> assert false) |> lsort)
     [1,"1"; 2,"2"; 3,"3"] \
-      (Assoc.update 3 [1,"1"; 2,"2"] \
+      (Assoc.update ~eq:CCInt.equal 3 [1,"1"; 2,"2"] \
         ~f:(function None -> Some "3" | _ -> assert false) |> lsort)
   *)
 
-  let remove ?(eq=(=)) x l =
+  let remove ~eq x l =
     search_set eq [] l x
       ~f:(fun _ opt_y rest -> match opt_y with
         | None -> l  (* keep as is *)
@@ -1305,14 +1305,19 @@ module Assoc = struct
 
   (*$=
     [1,"1"] \
-      (Assoc.remove 2 [1,"1"; 2,"2"] |> lsort)
+      (Assoc.remove ~eq:CCInt.equal 2 [1,"1"; 2,"2"] |> lsort)
     [1,"1"; 3,"3"] \
-      (Assoc.remove 2 [1,"1"; 2,"2"; 3,"3"] |> lsort)
+      (Assoc.remove ~eq:CCInt.equal 2 [1,"1"; 2,"2"; 3,"3"] |> lsort)
     [1,"1"; 2,"2"] \
-      (Assoc.remove 3 [1,"1"; 2,"2"] |> lsort)
+      (Assoc.remove ~eq:CCInt.equal 3 [1,"1"; 2,"2"] |> lsort)
   *)
 end
 
+let assoc = Assoc.get_exn
+let assoc_opt = Assoc.get
+let mem_assoc = Assoc.mem
+let remove_assoc = Assoc.remove
+
 (** {2 References on Lists} *)
 
 module Ref = struct
diff --git a/src/core/CCList.mli b/src/core/CCList.mli
index 17391f76..08e6b1a5 100644
--- a/src/core/CCList.mli
+++ b/src/core/CCList.mli
@@ -260,7 +260,7 @@ val find_idx : ('a -> bool) -> 'a t -> (int * 'a) option
 (** [find_idx p x] returns [Some (i,x)] where [x] is the [i]-th element of [l],
     and [p x] holds. Otherwise returns [None] *)
 
-val remove : ?eq:('a -> 'a -> bool) -> x:'a -> 'a t -> 'a t
+val remove : eq:('a -> 'a -> bool) -> x:'a -> 'a t -> 'a t
 (** [remove ~x l] removes every instance of [x] from [l]. Tailrec.
     @param eq equality function
     @since 0.11 *)
@@ -287,23 +287,23 @@ val all_ok : ('a, 'err) Result.result t -> ('a t, 'err) Result.result
     or [Error e] otherwise (with the first error met).
     @since 1.3 *)
 
-val sorted_merge : ?cmp:('a -> 'a -> int) -> 'a list -> 'a list -> 'a list
+val sorted_merge : cmp:('a -> 'a -> int) -> 'a list -> 'a list -> 'a list
 (** Merges elements from both sorted list *)
 
-val sort_uniq : ?cmp:('a -> 'a -> int) -> 'a list -> 'a list
+val sort_uniq : cmp:('a -> 'a -> int) -> 'a list -> 'a list
 (** Sort the list and remove duplicate elements *)
 
-val sorted_merge_uniq : ?cmp:('a -> 'a -> int) -> 'a list -> 'a list -> 'a list
+val sorted_merge_uniq : cmp:('a -> 'a -> int) -> 'a list -> 'a list -> 'a list
 (** [sorted_merge_uniq l1 l2] merges the sorted lists [l1] and [l2] and
     removes duplicates
     @since 0.10 *)
 
-val is_sorted : ?cmp:('a -> 'a -> int) -> 'a list -> bool
+val is_sorted : cmp:('a -> 'a -> int) -> 'a list -> bool
 (** [is_sorted l] returns [true] iff [l] is sorted (according to given order)
     @param cmp the comparison function (default [Pervasives.compare])
     @since 0.17 *)
 
-val sorted_insert : ?cmp:('a -> 'a -> int) -> ?uniq:bool -> 'a -> 'a list -> 'a list
+val sorted_insert : cmp:('a -> 'a -> int) -> ?uniq:bool -> 'a -> 'a list -> 'a list
 (** [sorted_insert x l] inserts [x] into [l] such that, if [l] was sorted,
     then [sorted_insert x l] is sorted too.
     @param uniq if true and [x] is already in sorted position in [l], then
@@ -313,17 +313,17 @@ val sorted_insert : ?cmp:('a -> 'a -> int) -> ?uniq:bool -> 'a -> 'a list -> 'a
 (*$Q
     Q.(pair small_int (list small_int)) (fun (x,l) -> \
       let l = List.sort Pervasives.compare l in \
-      is_sorted (sorted_insert x l))
+      is_sorted ~cmp:CCInt.compare (sorted_insert ~cmp:CCInt.compare x l))
 *)
 
-val uniq_succ : ?eq:('a -> 'a -> bool) -> 'a list -> 'a list
+val uniq_succ : eq:('a -> 'a -> bool) -> 'a list -> 'a list
 (** [uniq_succ l] removes duplicate elements that occur one next to the other.
     Examples:
     [uniq_succ [1;2;1] = [1;2;1]]
     [uniq_succ [1;1;2] = [1;2]]
     @since 0.10 *)
 
-val group_succ : ?eq:('a -> 'a -> bool) -> 'a list -> 'a list list
+val group_succ : eq:('a -> 'a -> bool) -> 'a list -> 'a list list
 (** [group_succ ~eq l] groups together consecutive elements that are equal
     according to [eq]
     @since 0.11 *)
@@ -376,30 +376,30 @@ val remove_at_idx : int -> 'a t -> 'a t
     Those operations maintain the invariant that the list does not
     contain duplicates (if it already satisfies it) *)
 
-val add_nodup : ?eq:('a -> 'a -> bool) -> 'a -> 'a t -> 'a t
+val add_nodup : eq:('a -> 'a -> bool) -> 'a -> 'a t -> 'a t
 (** [add_nodup x set] adds [x] to [set] if it was not already present. Linear time.
     @since 0.11 *)
 
-val remove_one : ?eq:('a -> 'a -> bool) -> 'a -> 'a t -> 'a t
+val remove_one : eq:('a -> 'a -> bool) -> 'a -> 'a t -> 'a t
 (** [remove_one x set] removes one occurrence of [x] from [set]. Linear time.
     @since 0.11 *)
 
-val mem : ?eq:('a -> 'a -> bool) -> 'a -> 'a t -> bool
+val mem : eq:('a -> 'a -> bool) -> 'a -> 'a t -> bool
 (** Membership to the list. Linear time *)
 
-val subset : ?eq:('a -> 'a -> bool) -> 'a t -> 'a t -> bool
+val subset : eq:('a -> 'a -> bool) -> 'a t -> 'a t -> bool
 (** Test for inclusion *)
 
-val uniq : ?eq:('a -> 'a -> bool) -> 'a t -> 'a t
+val uniq : eq:('a -> 'a -> bool) -> 'a t -> 'a t
 (** Remove duplicates w.r.t the equality predicate.
     Complexity is quadratic in the length of the list, but the order
     of elements is preserved. If you wish for a faster de-duplication
     but do not care about the order, use {!sort_uniq}*)
 
-val union : ?eq:('a -> 'a -> bool) -> 'a t -> 'a t -> 'a t
+val union : eq:('a -> 'a -> bool) -> 'a t -> 'a t -> 'a t
 (** List union. Complexity is product of length of inputs. *)
 
-val inter : ?eq:('a -> 'a -> bool) -> 'a t -> 'a t -> 'a t
+val inter : eq:('a -> 'a -> bool) -> 'a t -> 'a t -> 'a t
 (** List intersection. Complexity is product of length of inputs. *)
 
 (** {2 Other Constructors} *)
@@ -437,40 +437,52 @@ val repeat : int -> 'a t -> 'a t
 module Assoc : sig
   type ('a, 'b) t = ('a*'b) list
 
-  val get : ?eq:('a->'a->bool) -> 'a -> ('a,'b) t -> 'b option
+  val get : eq:('a->'a->bool) -> 'a -> ('a,'b) t -> 'b option
   (** Find the element *)
 
-  val get_exn : ?eq:('a->'a->bool) -> 'a -> ('a,'b) t -> 'b
+  val get_exn : eq:('a->'a->bool) -> 'a -> ('a,'b) t -> 'b
   (** Same as [get], but unsafe
       @raise Not_found if the element is not present *)
 
-  val set : ?eq:('a->'a->bool) -> 'a -> 'b -> ('a,'b) t -> ('a,'b) t
+  val set : eq:('a->'a->bool) -> 'a -> 'b -> ('a,'b) t -> ('a,'b) t
   (** Add the binding into the list (erase it if already present) *)
 
-  val mem : ?eq:('a->'a->bool) -> 'a -> ('a,_) t -> bool
+  val mem : eq:('a->'a->bool) -> 'a -> ('a,_) t -> bool
   (** [mem x l] returns [true] iff [x] is a key in [l]
       @since 0.16 *)
 
   val update :
-    ?eq:('a->'a->bool) -> f:('b option -> 'b option) -> 'a -> ('a,'b) t -> ('a,'b) t
+    eq:('a->'a->bool) -> f:('b option -> 'b option) -> 'a -> ('a,'b) t -> ('a,'b) t
   (** [update k ~f l] updates [l] on the key [k], by calling [f (get l k)]
       and removing [k] if it returns [None], mapping [k] to [v'] if it
       returns [Some v']
       @since 0.16 *)
 
-  val remove : ?eq:('a->'a->bool) -> 'a -> ('a,'b) t -> ('a,'b) t
+  val remove : eq:('a->'a->bool) -> 'a -> ('a,'b) t -> ('a,'b) t
   (** [remove x l] removes the first occurrence of [k] from [l].
       @since 0.17 *)
 end
 
-val assoc_opt : 'a -> ('a * 'b) t -> 'b option
-(** Safe version of {!assoc}
+val assoc : eq:('a -> 'a -> bool) -> 'a -> ('a * 'b) t -> 'b
+(** Same as [Assoc.get_exn]
+    @since NEXT_RELEASE *)
+
+val assoc_opt : eq:('a -> 'a -> bool) -> 'a -> ('a * 'b) t -> 'b option
+(** Same as [Assoc.get]
     @since 1.5 *)
 
 val assq_opt : 'a -> ('a * 'b) t -> 'b option
 (** Safe version of {!assq}
     @since 1.5 *)
 
+val mem_assoc : eq:('a -> 'a -> bool) -> 'a -> ('a * _) t -> bool
+(** Same as [Assoc.mem]
+    @since NEXT_RELEASE *)
+
+val remove_assoc : eq:('a -> 'a -> bool) -> 'a -> ('a * 'b) t -> ('a * 'b) t
+(** Same as [Assoc.remove]
+    @since NEXT_RELEASE *)
+
 (** {2 References on Lists}
     @since 0.3.3 *)
 
diff --git a/src/core/CCListLabels.mli b/src/core/CCListLabels.mli
index 4bc67737..ffa3d94b 100644
--- a/src/core/CCListLabels.mli
+++ b/src/core/CCListLabels.mli
@@ -178,7 +178,7 @@ val find_idx : f:('a -> bool) -> 'a t -> (int * 'a) option
 (** [find_idx p x] returns [Some (i,x)] where [x] is the [i]-th element of [l],
     and [p x] holds. Otherwise returns [None] *)
 
-val remove : ?eq:('a -> 'a -> bool) -> key:'a -> 'a t -> 'a t
+val remove : eq:('a -> 'a -> bool) -> key:'a -> 'a t -> 'a t
 (** [remove ~key l] removes every instance of [key] from [l]. Tailrec.
     @param eq equality function
     @since 0.11 *)
@@ -186,23 +186,23 @@ val remove : ?eq:('a -> 'a -> bool) -> key:'a -> 'a t -> 'a t
 val filter_map : f:('a -> 'b option) -> 'a t -> 'b t
 (** Map and remove elements at the same time *)
 
-val sorted_merge : ?cmp:('a -> 'a -> int) -> 'a list -> 'a list -> 'a list
+val sorted_merge : cmp:('a -> 'a -> int) -> 'a list -> 'a list -> 'a list
 (** Merges elements from both sorted list *)
 
-val sort_uniq : ?cmp:('a -> 'a -> int) -> 'a list -> 'a list
+val sort_uniq : cmp:('a -> 'a -> int) -> 'a list -> 'a list
 (** Sort the list and remove duplicate elements *)
 
-val sorted_merge_uniq : ?cmp:('a -> 'a -> int) -> 'a list -> 'a list -> 'a list
+val sorted_merge_uniq : cmp:('a -> 'a -> int) -> 'a list -> 'a list -> 'a list
 (** [sorted_merge_uniq l1 l2] merges the sorted lists [l1] and [l2] and
     removes duplicates
     @since 0.10 *)
 
-val is_sorted : ?cmp:('a -> 'a -> int) -> 'a list -> bool
+val is_sorted : cmp:('a -> 'a -> int) -> 'a list -> bool
 (** [is_sorted l] returns [true] iff [l] is sorted (according to given order)
     @param cmp the comparison function (default [Pervasives.compare])
     @since 0.17 *)
 
-val sorted_insert : ?cmp:('a -> 'a -> int) -> ?uniq:bool -> 'a -> 'a list -> 'a list
+val sorted_insert : cmp:('a -> 'a -> int) -> ?uniq:bool -> 'a -> 'a list -> 'a list
 (** [sorted_insert x l] inserts [x] into [l] such that, if [l] was sorted,
     then [sorted_insert x l] is sorted too.
     @param uniq if true and [x] is already in sorted position in [l], then
@@ -215,14 +215,14 @@ val sorted_insert : ?cmp:('a -> 'a -> int) -> ?uniq:bool -> 'a -> 'a list -> 'a
       is_sorted (sorted_insert x l))
 *)
 
-val uniq_succ : ?eq:('a -> 'a -> bool) -> 'a list -> 'a list
+val uniq_succ : eq:('a -> 'a -> bool) -> 'a list -> 'a list
 (** [uniq_succ l] removes duplicate elements that occur one next to the other.
     Examples:
     [uniq_succ [1;2;1] = [1;2;1]]
     [uniq_succ [1;1;2] = [1;2]]
     @since 0.10 *)
 
-val group_succ : ?eq:('a -> 'a -> bool) -> 'a list -> 'a list list
+val group_succ : eq:('a -> 'a -> bool) -> 'a list -> 'a list list
 (** [group_succ ~eq l] groups together consecutive elements that are equal
     according to [eq]
     @since 0.11 *)
@@ -259,30 +259,30 @@ val remove_at_idx : int -> 'a t -> 'a t
     Those operations maintain the invariant that the list does not
     contain duplicates (if it already satisfies it) *)
 
-val add_nodup : ?eq:('a -> 'a -> bool) -> 'a -> 'a t -> 'a t
+val add_nodup : eq:('a -> 'a -> bool) -> 'a -> 'a t -> 'a t
 (** [add_nodup x set] adds [x] to [set] if it was not already present. Linear time.
     @since 0.11 *)
 
-val remove_one : ?eq:('a -> 'a -> bool) -> 'a -> 'a t -> 'a t
+val remove_one : eq:('a -> 'a -> bool) -> 'a -> 'a t -> 'a t
 (** [remove_one x set] removes one occurrence of [x] from [set]. Linear time.
     @since 0.11 *)
 
-val mem : ?eq:('a -> 'a -> bool) -> 'a -> 'a t -> bool
+val mem : eq:('a -> 'a -> bool) -> 'a -> 'a t -> bool
 (** Membership to the list. Linear time *)
 
-val subset : ?eq:('a -> 'a -> bool) -> 'a t -> 'a t -> bool
+val subset : eq:('a -> 'a -> bool) -> 'a t -> 'a t -> bool
 (** Test for inclusion *)
 
-val uniq : ?eq:('a -> 'a -> bool) -> 'a t -> 'a t
+val uniq : eq:('a -> 'a -> bool) -> 'a t -> 'a t
 (** Remove duplicates w.r.t the equality predicate.
     Complexity is quadratic in the length of the list, but the order
     of elements is preserved. If you wish for a faster de-duplication
     but do not care about the order, use {!sort_uniq}*)
 
-val union : ?eq:('a -> 'a -> bool) -> 'a t -> 'a t -> 'a t
+val union : eq:('a -> 'a -> bool) -> 'a t -> 'a t -> 'a t
 (** List union. Complexity is product of length of inputs. *)
 
-val inter : ?eq:('a -> 'a -> bool) -> 'a t -> 'a t -> 'a t
+val inter : eq:('a -> 'a -> bool) -> 'a t -> 'a t -> 'a t
 (** List intersection. Complexity is product of length of inputs. *)
 
 (** {2 Other Constructors} *)
@@ -320,32 +320,52 @@ val repeat : int -> 'a t -> 'a t
 module Assoc : sig
   type ('a, 'b) t = ('a*'b) list
 
-  val get : ?eq:('a->'a->bool) -> 'a -> ('a,'b) t -> 'b option
+  val get : eq:('a->'a->bool) -> 'a -> ('a,'b) t -> 'b option
   (** Find the element *)
 
-  val get_exn : ?eq:('a->'a->bool) -> 'a -> ('a,'b) t -> 'b
+  val get_exn : eq:('a->'a->bool) -> 'a -> ('a,'b) t -> 'b
   (** Same as [get], but unsafe
       @raise Not_found if the element is not present *)
 
-  val set : ?eq:('a->'a->bool) -> 'a -> 'b -> ('a,'b) t -> ('a,'b) t
+  val set : eq:('a->'a->bool) -> 'a -> 'b -> ('a,'b) t -> ('a,'b) t
   (** Add the binding into the list (erase it if already present) *)
 
-  val mem : ?eq:('a->'a->bool) -> 'a -> ('a,_) t -> bool
+  val mem : eq:('a->'a->bool) -> 'a -> ('a,_) t -> bool
   (** [mem x l] returns [true] iff [x] is a key in [l]
       @since 0.16 *)
 
   val update :
-    ?eq:('a->'a->bool) -> f:('b option -> 'b option) -> 'a -> ('a,'b) t -> ('a,'b) t
+    eq:('a->'a->bool) -> f:('b option -> 'b option) -> 'a -> ('a,'b) t -> ('a,'b) t
   (** [update k ~f l] updates [l] on the key [k], by calling [f (get l k)]
       and removing [k] if it returns [None], mapping [k] to [v'] if it
       returns [Some v']
       @since 0.16 *)
 
-  val remove : ?eq:('a->'a->bool) -> 'a -> ('a,'b) t -> ('a,'b) t
+  val remove : eq:('a->'a->bool) -> 'a -> ('a,'b) t -> ('a,'b) t
   (** [remove x l] removes the first occurrence of [k] from [l].
       @since 0.17 *)
 end
 
+val assoc : eq:('a -> 'a -> bool) -> 'a -> ('a * 'b) t -> 'b
+(** Same as [Assoc.get_exn]
+    @since NEXT_RELEASE *)
+
+val assoc_opt : eq:('a -> 'a -> bool) -> 'a -> ('a * 'b) t -> 'b option
+(** Same as [Assoc.get]
+    @since NEXT_RELEASE *)
+
+val assq_opt : 'a -> ('a * 'b) t -> 'b option
+(** Safe version of {!assq}
+    @since NEXT_RELEASE *)
+
+val mem_assoc : eq:('a -> 'a -> bool) -> 'a -> ('a * _) t -> bool
+(** Same as [Assoc.mem]
+    @since NEXT_RELEASE *)
+
+val remove_assoc : eq:('a -> 'a -> bool) -> 'a -> ('a * 'b) t -> ('a * 'b) t
+(** Same as [Assoc.remove]
+    @since NEXT_RELEASE *)
+
 (** {2 References on Lists}
     @since 0.3.3 *)
 
diff --git a/src/core/CCParse.ml b/src/core/CCParse.ml
index f581784a..229895f0 100644
--- a/src/core/CCParse.ml
+++ b/src/core/CCParse.ml
@@ -43,6 +43,9 @@ type state = {
 
 exception ParseError of parse_branch * (unit -> string)
 
+let char_equal (a : char) b = Pervasives.(=) a b
+let string_equal (a : string) b = Pervasives.(=) a b
+
 let rec string_of_branch l =
   let pp_s () = function
     | None -> ""
@@ -87,7 +90,7 @@ let next st ~ok ~err =
   else (
     let c = st.str.[st.i] in
     st.i <- st.i + 1;
-    if c='\n'
+    if char_equal c '\n'
     then (st.lnum <- st.lnum + 1; st.cnum <- 1)
     else st.cnum <- st.cnum + 1;
     ok c
@@ -146,7 +149,7 @@ let char c =
   let msg = Printf.sprintf "expected '%c'" c in
   fun st ~ok ~err ->
     next st ~err
-      ~ok:(fun c' -> if c=c' then ok c else fail_ ~err st (const_ msg))
+      ~ok:(fun c' -> if char_equal c c' then ok c else fail_ ~err st (const_ msg))
 
 let char_if p st ~ok ~err =
   next st ~err
@@ -164,7 +167,7 @@ let chars_if p st ~ok ~err:_ =
 let chars1_if p st ~ok ~err =
   chars_if p st ~err
     ~ok:(fun s ->
-      if s = ""
+      if string_equal s ""
       then fail_ ~err st (const_ "unexpected sequence of chars")
       else ok s)
 
@@ -231,7 +234,7 @@ let string s st ~ok ~err =
     else
       next st ~err
         ~ok:(fun c ->
-          if c = s.[i]
+          if char_equal c s.[i]
           then check (i+1)
           else fail_ ~err st (fun () -> Printf.sprintf "expected \"%s\"" s))
   in
@@ -386,7 +389,7 @@ module U = struct
       skip_white <* string stop
 
   let int =
-    chars1_if (fun c -> is_num c || c='-')
+    chars1_if (fun c -> is_num c || char_equal c '-')
     >>= fun s ->
     try return (int_of_string s)
     with Failure _ -> fail "expected an int"
diff --git a/src/core/CCRandom.ml b/src/core/CCRandom.ml
index bcc83111..fc3d7d93 100644
--- a/src/core/CCRandom.ml
+++ b/src/core/CCRandom.ml
@@ -77,7 +77,7 @@ let replicate n g st =
   in aux [] n
 
 (* Sample without replacement using rejection sampling. *)
-let sample_without_replacement (type elt)  ?(compare=compare) k (rng:elt t) st=
+let sample_without_replacement (type elt) ~compare k (rng:elt t) st=
   let module S = Set.Make(struct type t=elt let compare = compare end) in
   let rec aux s k =
     if k <= 0 then
@@ -118,7 +118,7 @@ let _diff_list ~last l =
 let split_list i ~len st =
   if len <= 1 then invalid_arg "Random.split_list";
   if i >= len then
-    let xs = sample_without_replacement (len-1) (int_range 1 (i-1)) st in
+    let xs = sample_without_replacement ~compare (len-1) (int_range 1 (i-1)) st in
     _diff_list ( 0::xs ) ~last:i
   else
     None
@@ -221,6 +221,7 @@ let uniformity_test ?(size_hint=10) k rng st =
   let confidence = 4. in
   let std = confidence *. (sqrt (kf *. variance)) in
   let predicate _key n acc =
+    let (<) (a : float) b = Pervasives.(<) a b in
     acc && abs_float (average -. float_of_int n) < std in
   Hashtbl.fold predicate histogram true
 
diff --git a/src/core/CCRandom.mli b/src/core/CCRandom.mli
index ffb32cfb..de76e90d 100644
--- a/src/core/CCRandom.mli
+++ b/src/core/CCRandom.mli
@@ -56,7 +56,7 @@ val replicate : int -> 'a t -> 'a list t
     randomly using [g] *)
 
 val sample_without_replacement:
-  ?compare:('a -> 'a -> int) -> int -> 'a t -> 'a list t
+  compare:('a -> 'a -> int) -> int -> 'a t -> 'a list t
 (** [sample_without_replacement n g] makes a list of [n] elements which are all
     generated randomly using [g] with the added constraint that none of the generated
     random values are equal
diff --git a/src/core/CCResult.ml b/src/core/CCResult.ml
index 271c4823..362d7b4d 100644
--- a/src/core/CCResult.ml
+++ b/src/core/CCResult.ml
@@ -109,12 +109,12 @@ let (>|=) e f = map f e
 
 let (>>=) e f = flat_map f e
 
-let equal ?(err=Pervasives.(=)) eq a b = match a, b with
+let equal ~err eq a b = match a, b with
   | Ok x, Ok y -> eq x y
   | Error s, Error s' -> err s s'
   | _ -> false
 
-let compare ?(err=Pervasives.compare) cmp a b = match a, b with
+let compare ~err cmp a b = match a, b with
   | Ok x, Ok y -> cmp x y
   | Ok _, _  -> 1
   | _, Ok _ -> -1
diff --git a/src/core/CCResult.mli b/src/core/CCResult.mli
index a494081a..15e4d53a 100644
--- a/src/core/CCResult.mli
+++ b/src/core/CCResult.mli
@@ -96,9 +96,9 @@ val (>|=) : ('a, 'err) t -> ('a -> 'b) -> ('b, 'err) t
 
 val (>>=) : ('a, 'err) t -> ('a -> ('b, 'err) t) -> ('b, 'err) t
 
-val equal : ?err:'err equal -> 'a equal -> ('a, 'err) t equal
+val equal : err:'err equal -> 'a equal -> ('a, 'err) t equal
 
-val compare : ?err:'err ord -> 'a ord -> ('a, 'err) t ord
+val compare : err:'err ord -> 'a ord -> ('a, 'err) t ord
 
 val fold : ok:('a -> 'b) -> error:('err -> 'b) -> ('a, 'err) t -> 'b
 (** [fold ~ok ~error e] opens [e] and, if [e = Ok x], returns
diff --git a/src/core/CCString.ml b/src/core/CCString.ml
index 9654760d..6e66c732 100644
--- a/src/core/CCString.ml
+++ b/src/core/CCString.ml
@@ -56,8 +56,9 @@ module type S = sig
   val print : Format.formatter -> t -> unit
 end
 
-let equal (a:string) b = a=b
+let equal (a:string) b = Pervasives.(=) a b
 
+let compare_int (a : int) b = Pervasives.compare a b
 let compare = String.compare
 
 let hash s = Hashtbl.hash s
@@ -78,7 +79,7 @@ let _is_sub ~sub i s j ~len =
   let rec check k =
     if k = len
     then true
-    else sub.[i+k] = s.[j+k] && check (k+1)
+    else CCChar.equal sub.[i+k] s.[j+k] && check (k+1)
   in
   j+len <= String.length s && check 0
 
@@ -126,7 +127,7 @@ module Find = struct
           let j = ref 0 in
           while !i < len do
             match !j with
-              | _ when get str (!i-1) = get str !j ->
+              | _ when CCChar.equal (get str (!i-1)) (get str !j) ->
                 (* substring starting at !j continues matching current char *)
                 incr j;
                 failure.(!i) <- !j;
@@ -158,7 +159,7 @@ module Find = struct
     while !j < pat_len && !i + !j < len do
       let c = String.get s (!i + !j) in
       let expected = String.get pattern.str !j in
-      if c = expected
+      if CCChar.equal c expected
       then (
         (* char matches *)
         incr j;
@@ -193,7 +194,7 @@ module Find = struct
     while !j < pat_len && !i + !j < len do
       let c = String.get s (len - !i - !j - 1) in
       let expected = String.get pattern.str (String.length pattern.str - !j - 1) in
-      if c = expected
+      if CCChar.equal c expected
       then (
         (* char matches *)
         incr j;
@@ -292,7 +293,7 @@ let replace_at_ ~pos ~len ~by s =
   Buffer.contents b
 
 let replace ?(which=`All) ~sub ~by s =
-  if sub="" then invalid_arg "CCString.replace";
+  if is_empty sub then invalid_arg "CCString.replace";
   match which with
     | `Left ->
       let i = find ~sub s ~start:0 in
@@ -442,7 +443,7 @@ let compare_versions a b =
         | Some _, None -> 1
         | None, Some _ -> -1
         | Some x, Some y ->
-          let c = Pervasives.compare x y in
+          let c = compare_int x y in
           if c<>0 then c else cmp_rec a b
   in
   cmp_rec (Split.gen_cpy ~by:"." a) (Split.gen_cpy ~by:"." b)
@@ -480,7 +481,7 @@ let compare_natural a b =
         | NC_int _, NC_char _ -> 1
         | NC_char _, NC_int _ -> -1
         | NC_int x, NC_int y ->
-          let c = Pervasives.compare x y in
+          let c = compare_int x y in
           if c<>0 then c else cmp_rec a b
   in
   cmp_rec (chunks a) (chunks b)
@@ -490,7 +491,7 @@ let edit_distance s1 s2 =
   then length s2
   else if length s2 = 0
   then length s1
-  else if s1 = s2
+  else if equal s1 s2
   then 0
   else begin
     (* distance vectors (v0=previous, v1=current) *)
@@ -777,14 +778,9 @@ let exists2 p s1 s2 =
     (** {2 Ascii functions} *)
 
 let equal_caseless s1 s2: bool =
-  let char_lower c =
-    if c >= 'A' && c <= 'Z'
-    then Char.unsafe_chr (Char. code c + 32)
-    else c
-  in
   String.length s1 = String.length s2 &&
   for_all2
-    (fun c1 c2 -> char_lower c1 = char_lower c2)
+    (fun c1 c2 -> CCChar.equal (CCChar.lowercase_ascii c1) (CCChar.lowercase_ascii c2))
     s1 s2
 
 let pp buf s =
diff --git a/src/core/CCVector.ml b/src/core/CCVector.ml
index 13586ae7..32d4bb33 100644
--- a/src/core/CCVector.ml
+++ b/src/core/CCVector.ml
@@ -297,7 +297,7 @@ let compare cmp v1 v2 =
   let n = min v1.size v2.size in
   let rec check i =
     if i = n
-    then Pervasives.compare v1.size v2.size
+    then compare v1.size v2.size
     else
       let c = cmp (get v1 i) (get v2 i) in
       if c = 0 then check (i+1) else c
@@ -513,7 +513,7 @@ let for_all p v =
     else p v.vec.(i) && check (i+1)
   in check 0
 
-let member ?(eq=(=)) x v =
+let member ~eq x v =
   exists (eq x) v
 
 let find_exn p v =
diff --git a/src/core/CCVector.mli b/src/core/CCVector.mli
index edb60897..b570905e 100644
--- a/src/core/CCVector.mli
+++ b/src/core/CCVector.mli
@@ -118,7 +118,7 @@ val shrink : ('a, rw) t -> int -> unit
 (** Shrink to the given size (remove elements above this size).
     Does nothing if the parameter is bigger than the current size. *)
 
-val member : ?eq:('a -> 'a -> bool) -> 'a -> ('a, _) t -> bool
+val member : eq:('a -> 'a -> bool) -> 'a -> ('a, _) t -> bool
 (** Is the element a member of the vector? *)
 
 val sort : ('a -> 'a -> int) -> ('a, _) t -> ('a, 'mut) t
diff --git a/src/core/containers.ml b/src/core/containers.ml
index cb3f4814..6db033eb 100644
--- a/src/core/containers.ml
+++ b/src/core/containers.ml
@@ -42,3 +42,6 @@ module Result = CCResult
 module Set = CCSet
 module String = CCString
 module Vector = CCVector
+module Monomorphic = CCMonomorphic
+
+include Monomorphic
diff --git a/src/data/CCCache.ml b/src/data/CCCache.ml
index ec956458..e8cf3426 100644
--- a/src/data/CCCache.ml
+++ b/src/data/CCCache.ml
@@ -6,7 +6,6 @@
 type 'a equal = 'a -> 'a -> bool
 type 'a hash = 'a -> int
 
-let default_eq_ = Pervasives.(=)
 let default_hash_ = Hashtbl.hash
 
 (** {2 Value interface} *)
@@ -57,7 +56,7 @@ let with_cache_rec ?(cb=default_callback_) c f =
   f'
 
 (*$R
-  let c = unbounded 256 in
+  let c = unbounded ~eq:CCInt.equal 256 in
   let fib = with_cache_rec c
     (fun self n -> match n with
       | 1 | 2 -> 1
@@ -124,7 +123,7 @@ module Linear = struct
     !r
 end
 
-let linear ?(eq=default_eq_) size =
+let linear ~eq size =
   let size = max size 1 in
   let arr = Linear.make eq size in
   { get=(fun x -> Linear.get arr x);
@@ -161,9 +160,13 @@ module Replacing = struct
       | Pair _
       | Empty -> raise Not_found
 
+  let is_empty = function
+    | Empty -> true
+    | Pair _ -> false
+
   let set c x y =
     let i = c.hash x mod Array.length c.arr in
-    if c.arr.(i) = Empty then c.c_size <- c.c_size + 1;
+    if is_empty c.arr.(i) then c.c_size <- c.c_size + 1;
     c.arr.(i) <- Pair (x,y)
 
   let iter c f =
@@ -172,7 +175,7 @@ module Replacing = struct
   let size c () = c.c_size
 end
 
-let replacing ?(eq=default_eq_) ?(hash=default_hash_) size =
+let replacing ~eq ?(hash=default_hash_) size =
   let c = Replacing.make eq hash size in
   { get=(fun x -> Replacing.get c x);
     set=(fun x y -> Replacing.set c x y);
@@ -219,7 +222,7 @@ module LRU(X:HASH) = struct
   (* take first from queue *)
   let take_ c =
     match c.first with
-      | Some n when n.next == n ->
+      | Some n when Pervasives.(==) n.next n ->
         (* last element *)
         c.first <- None;
         n
@@ -238,7 +241,7 @@ module LRU(X:HASH) = struct
         n.next <- n;
         n.prev <- n;
         c.first <- Some n
-      | Some n1 when n1==n -> ()
+      | Some n1 when Pervasives.(==) n1 n -> ()
       | Some n1 ->
         n.prev <- n1.prev;
         n.next <- n1;
@@ -294,7 +297,7 @@ module LRU(X:HASH) = struct
     H.iter (fun x node -> f x node.value) c.table
 end
 
-let lru (type a) ?(eq=default_eq_) ?(hash=default_hash_) size =
+let lru (type a) ~eq ?(hash=default_hash_) size =
   let module L = LRU(struct
       type t = a
       let equal = eq
@@ -318,7 +321,7 @@ let lru (type a) ?(eq=default_eq_) ?(hash=default_hash_) size =
 
 (*$T
   let f = (let r = ref 0 in fun _ -> incr r; !r) in \
-  let c = lru 2 in \
+  let c = lru ~eq:CCInt.equal 2 in \
   let res1 = with_cache c f 1 in \
   let res2 = with_cache c f 2 in \
   let res3 = with_cache c f 3 in \
@@ -328,7 +331,7 @@ let lru (type a) ?(eq=default_eq_) ?(hash=default_hash_) size =
 
 (*$R
   let f = (let r = ref 0 in fun _ -> incr r; !r) in
-  let c = lru 2 in
+  let c = lru ~eq:CCEqual.unit 2 in
   let x = with_cache c f () in
   assert_equal 1 x;
   assert_equal 1 (size c);
@@ -356,7 +359,7 @@ module UNBOUNDED(X:HASH) = struct
   let iter c f = H.iter f c
 end
 
-let unbounded (type a) ?(eq=default_eq_) ?(hash=default_hash_) size =
+let unbounded (type a) ~eq ?(hash=default_hash_) size =
   let module C = UNBOUNDED(struct
       type t = a
       let equal = eq
diff --git a/src/data/CCCache.mli b/src/data/CCCache.mli
index 28c287b2..4d1121b5 100644
--- a/src/data/CCCache.mli
+++ b/src/data/CCCache.mli
@@ -79,13 +79,13 @@ val add : ('a, 'b) t -> 'a -> 'b -> bool
 val dummy : ('a,'b) t
 (** Dummy cache, never stores any value *)
 
-val linear : ?eq:'a equal -> int -> ('a, 'b) t
+val linear : eq:'a equal -> int -> ('a, 'b) t
 (** Linear cache with the given size. It stores key/value pairs in
     an array and does linear search at every call, so it should only be used
     with small size.
     @param eq optional equality predicate for keys *)
 
-val replacing : ?eq:'a equal -> ?hash:'a hash ->
+val replacing : eq:'a equal -> ?hash:'a hash ->
   int -> ('a,'b) t
 (** Replacing cache of the given size. Equality and hash functions can be
     parametrized. It's a hash table that handles collisions by replacing
@@ -93,12 +93,12 @@ val replacing : ?eq:'a equal -> ?hash:'a hash ->
     entry with the same hash (modulo size) is added).
     Never grows wider than the given size. *)
 
-val lru : ?eq:'a equal -> ?hash:'a hash ->
+val lru : eq:'a equal -> ?hash:'a hash ->
   int -> ('a,'b) t
 (** LRU cache of the given size ("Least Recently Used": keys that have not been
     used recently are deleted first). Never grows wider than the given size. *)
 
-val unbounded : ?eq:'a equal -> ?hash:'a hash ->
+val unbounded : eq:'a equal -> ?hash:'a hash ->
   int -> ('a,'b) t
 (** Unbounded cache, backed by a Hash table. Will grow forever
     unless {!clear} is called manually. *)
diff --git a/src/data/CCDeque.ml b/src/data/CCDeque.ml
index 9453e464..7a91f4c7 100644
--- a/src/data/CCDeque.ml
+++ b/src/data/CCDeque.ml
@@ -74,9 +74,11 @@ let is_zero_ n = match n.cell with
   | Two _
   | Three _ -> false
 
+let bool_eq (a : bool) b = Pervasives.(=) a b
+
 let is_empty d =
   let res = d.size = 0 in
-  assert (res = is_zero_ d.cur);
+  assert (bool_eq res (is_zero_ d.cur));
   res
 
 let push_front d x =
@@ -161,7 +163,7 @@ let take_back_node_ n = match n.cell with
 
 let take_back d =
   if is_empty d then raise Empty
-  else if d.cur == d.cur.prev
+  else if Pervasives.(==) d.cur d.cur.prev
   then (
     (* only one cell *)
     decr_size_ d;
@@ -194,7 +196,7 @@ let take_front_node_ n = match n.cell with
 
 let take_front d =
   if is_empty d then raise Empty
-  else if d.cur.prev == d.cur
+  else if Pervasives.(==) d.cur.prev d.cur
   then (
     (* only one cell *)
     decr_size_ d;
@@ -253,7 +255,7 @@ let fold f acc d =
       | Two (x,y) -> f (f acc x) y
       | Three (x,y,z) -> f (f (f acc x) y) z
     in
-    if n.next == first then acc else aux ~first f acc n.next
+    if Pervasives.(==) n.next first then acc else aux ~first f acc n.next
   in
   aux ~first:d.cur f acc d.cur
 
@@ -335,7 +337,7 @@ let to_gen q =
   let cell = ref q.cur.cell in
   let cur = ref q.cur in
   let rec next () = match !cell with
-    | Zero when (!cur).next == first -> None
+    | Zero when Pervasives.(==) (!cur).next first -> None
     | Zero ->
       (* go to next node *)
       let n = !cur in
@@ -367,7 +369,7 @@ let copy d =
   let q = of_list [1;2;3;4] in
   assert_equal 4 (length q);
   let q' = copy q in
-  let cmp = equal ?eq:None in
+  let cmp = equal ~eq:CCInt.equal in
   assert_equal 4 (length q');
   assert_equal ~cmp q q';
   push_front q 0;
@@ -377,7 +379,7 @@ let copy d =
   assert_equal ~cmp q q'
 *)
 
-let equal ?(eq=(=)) a b =
+let equal ~eq a b =
   let rec aux eq a b = match a() , b() with
     | None, None -> true
     | None, Some _
@@ -385,7 +387,7 @@ let equal ?(eq=(=)) a b =
     | Some x, Some y -> eq x y && aux eq a b
   in aux eq (to_gen a) (to_gen b)
 
-let compare ?(cmp=Pervasives.compare) a b =
+let compare ~cmp a b =
   let rec aux cmp a b = match a() , b() with
     | None, None -> 0
     | None, Some _ -> -1
@@ -397,7 +399,7 @@ let compare ?(cmp=Pervasives.compare) a b =
 
 (*$Q
    Q.(pair (list int) (list int)) (fun (l1,l2) -> \
-    CCOrd.equiv (compare (of_list l1) (of_list l2)) \
+    CCOrd.equiv (compare ~cmp:Pervasives.compare (of_list l1) (of_list l2)) \
       (CCList.compare Pervasives.compare l1 l2))
 *)
 
@@ -412,4 +414,3 @@ let print pp_x out d =
        pp_x out x
     ) d;
   Format.fprintf out "}@]"
-
diff --git a/src/data/CCDeque.mli b/src/data/CCDeque.mli
index c0bde886..4571f63a 100644
--- a/src/data/CCDeque.mli
+++ b/src/data/CCDeque.mli
@@ -21,13 +21,13 @@ val clear : _ t -> unit
 val is_empty : 'a t -> bool
 (** Is the deque empty? *)
 
-val equal : ?eq:('a -> 'a -> bool) -> 'a t -> 'a t -> bool
+val equal : eq:('a -> 'a -> bool) -> 'a t -> 'a t -> bool
 (** [equal a b] checks whether [a] and [b] contain the same sequence of
     elements.
     @param eq comparison function for elements
     @since 0.13 *)
 
-val compare : ?cmp:('a -> 'a -> int) -> 'a t -> 'a t -> int
+val compare : cmp:('a -> 'a -> int) -> 'a t -> 'a t -> int
 (** [compare a b] compares lexicographically [a] and [b]
     @param cmp comparison function for elements
     @since 0.13 *)
diff --git a/src/data/CCFQueue.ml b/src/data/CCFQueue.ml
index de6848f1..44b0662f 100644
--- a/src/data/CCFQueue.ml
+++ b/src/data/CCFQueue.ml
@@ -34,10 +34,14 @@ let empty = Shallow Zero
 
 exception Empty
 
+let is_not_zero = function
+  | Zero -> false
+  | One _ | Two _ | Three _ -> true
+
 let _single x = Shallow (One x)
 let _double x y = Shallow (Two (x,y))
 let _deep n hd middle tl =
-  assert (hd<>Zero && tl<>Zero);
+  assert (is_not_zero hd && is_not_zero tl);
   Deep (n, hd, middle, tl)
 
 let is_empty = function
diff --git a/src/data/CCGraph.ml b/src/data/CCGraph.ml
index 067f9c3d..63c889fb 100644
--- a/src/data/CCGraph.ml
+++ b/src/data/CCGraph.ml
@@ -56,7 +56,7 @@ type ('k, 'a) table = {
 (** Mutable set *)
 type 'a set = ('a, unit) table
 
-let mk_table (type k) ?(eq=(=)) ?(hash=Hashtbl.hash) size =
+let mk_table (type k) ~eq ?(hash=Hashtbl.hash) size =
   let module H = Hashtbl.Make(struct
       type t = k
       let equal = eq
@@ -68,7 +68,7 @@ let mk_table (type k) ?(eq=(=)) ?(hash=Hashtbl.hash) size =
   ; add=(fun k v -> H.replace tbl k v)
   }
 
-let mk_map (type k) ?(cmp=Pervasives.compare) () =
+let mk_map (type k) ~cmp () =
   let module M = Map.Make(struct
       type t = k
       let compare = cmp
@@ -160,15 +160,15 @@ module Traverse = struct
         )
       done
 
-  let generic ?(tbl=mk_table 128) ~bag ~graph seq =
+  let generic ~tbl ~bag ~graph seq =
     let tags = {
       get_tag=tbl.mem;
       set_tag=(fun v -> tbl.add v ());
     } in
     generic_tag ~tags ~bag ~graph seq
 
-  let bfs ?tbl ~graph seq =
-    generic ?tbl ~bag:(mk_queue ()) ~graph seq
+  let bfs ~tbl ~graph seq =
+    generic ~tbl ~bag:(mk_queue ()) ~graph seq
 
   let bfs_tag ~tags ~graph seq =
     generic_tag ~tags ~bag:(mk_queue()) ~graph seq
@@ -186,15 +186,15 @@ module Traverse = struct
     let bag = mk_heap ~leq:(fun (_,d1,_) (_,d2,_) -> d1 <= d2) in
     generic_tag ~tags:tags' ~bag ~graph:graph' seq'
 
-  let dijkstra ?(tbl=mk_table 128) ?dist ~graph seq =
+  let dijkstra ~tbl ?dist ~graph seq =
     let tags = {
       get_tag=tbl.mem;
       set_tag=(fun v -> tbl.add v ());
     } in
     dijkstra_tag ~tags ?dist ~graph seq
 
-  let dfs ?tbl ~graph seq =
-    generic ?tbl ~bag:(mk_stack ()) ~graph seq
+  let dfs ~tbl ~graph seq =
+    generic ~tbl ~bag:(mk_stack ()) ~graph seq
 
   let dfs_tag ~tags ~graph seq =
     generic_tag ~tags ~bag:(mk_stack()) ~graph seq
@@ -240,7 +240,7 @@ module Traverse = struct
       | (v1,_,_) :: path' ->
         eq v v1 || list_mem_ ~eq ~graph v path'
 
-    let dfs_tag ?(eq=(=)) ~tags ~graph seq =
+    let dfs_tag ~eq ~tags ~graph seq =
       let first = ref true in
       fun k ->
         if !first then first := false else raise Sequence_once;
@@ -279,17 +279,18 @@ module Traverse = struct
              done
           ) seq
 
-    let dfs ?(tbl=mk_table 128) ?eq ~graph seq =
+    let dfs ~tbl ~eq ~graph seq =
       let tags = {
         set_tag=(fun v -> tbl.add v ());
         get_tag=tbl.mem;
       } in
-      dfs_tag ?eq ~tags ~graph seq
+      dfs_tag ~eq ~tags ~graph seq
   end
 
   (*$R
     let l =
-      Traverse.Event.dfs ~graph:divisors_graph (Sequence.return 345614)
+      let tbl = mk_table ~eq:CCInt.equal 128 in
+      Traverse.Event.dfs ~tbl ~eq:CCInt.equal ~graph:divisors_graph (Sequence.return 345614)
       |> Sequence.to_list in
     let expected =
     [`Enter (345614, 0, []); `Edge (345614, (), 172807, `Forward);
@@ -305,8 +306,8 @@ end
 
 (** {2 Cycles} *)
 
-let is_dag ?(tbl=mk_table 128) ~graph vs =
-  Traverse.Event.dfs ~tbl ~graph vs
+let is_dag ~tbl ~eq ~graph vs =
+  Traverse.Event.dfs ~tbl ~eq ~graph vs
   |> Seq.exists_
     (function
       | `Edge (_, _, _, `Back) -> true
@@ -316,7 +317,7 @@ let is_dag ?(tbl=mk_table 128) ~graph vs =
 
 exception Has_cycle
 
-let topo_sort_tag ?(eq=(=)) ?(rev=false) ~tags ~graph seq =
+let topo_sort_tag ~eq ?(rev=false) ~tags ~graph seq =
   (* use DFS *)
   let l =
     Traverse.Event.dfs_tag ~eq ~tags ~graph seq
@@ -331,21 +332,23 @@ let topo_sort_tag ?(eq=(=)) ?(rev=false) ~tags ~graph seq =
   in
   if rev then List.rev l else l
 
-let topo_sort ?eq ?rev ?(tbl=mk_table 128) ~graph seq =
+let topo_sort ~eq ?rev ~tbl ~graph seq =
   let tags = {
     get_tag=tbl.mem;
     set_tag=(fun v -> tbl.add v ());
   } in
-  topo_sort_tag ?eq ?rev ~tags ~graph seq
+  topo_sort_tag ~eq ?rev ~tags ~graph seq
 
 (*$T
-  let l = topo_sort ~graph:divisors_graph (Seq.return 42) in \
+  let tbl = mk_table ~eq:CCInt.equal 128 in \
+  let l = topo_sort ~tbl ~eq:CCInt.equal ~graph:divisors_graph (Seq.return 42) in \
   List.for_all (fun (i,j) -> \
     let idx_i = CCList.find_idx ((=)i) l |> CCOpt.get_exn |> fst in \
     let idx_j = CCList.find_idx ((=)j) l |> CCOpt.get_exn |> fst in \
     idx_i < idx_j) \
     [ 42, 21; 14, 2; 3, 1; 21, 7; 42, 3]
-  let l = topo_sort ~rev:true ~graph:divisors_graph (Seq.return 42) in \
+  let tbl = mk_table ~eq:CCInt.equal 128 in \
+  let l = topo_sort ~tbl ~eq:CCInt.equal ~rev:true ~graph:divisors_graph (Seq.return 42) in \
   List.for_all (fun (i,j) -> \
     let idx_i = CCList.find_idx ((=)i) l |> CCOpt.get_exn |> fst in \
     let idx_j = CCList.find_idx ((=)j) l |> CCOpt.get_exn |> fst in \
@@ -393,7 +396,7 @@ let spanning_tree_tag ~tags ~graph v =
   in
   mk_node v
 
-let spanning_tree ?(tbl=mk_table 128) ~graph v =
+let spanning_tree ~tbl ~graph v =
   let tags = {
     get_tag=tbl.mem;
     set_tag=(fun v -> tbl.add v ());
@@ -482,12 +485,12 @@ end
 
 type 'v scc_state = 'v SCC.state
 
-let scc ?(tbl=mk_table 128) ~graph seq = SCC.explore ~tbl ~graph seq
+let scc ~tbl ~graph seq = SCC.explore ~tbl ~graph seq
 
 (* example from https://en.wikipedia.org/wiki/Strongly_connected_component *)
 (*$R
   let set_eq ?(eq=(=)) l1 l2 = CCList.subset ~eq l1 l2 && CCList.subset ~eq l2 l1 in
-  let graph = of_list
+  let graph = of_list ~eq:CCString.equal
     [ "a", "b"
     ; "b", "e"
     ; "e", "a"
@@ -503,7 +506,8 @@ let scc ?(tbl=mk_table 128) ~graph seq = SCC.explore ~tbl ~graph seq
     ; "h", "d"
     ; "h", "g"
   ] in
-  let res = scc ~graph (Seq.return "a") |> Seq.to_list in
+  let tbl = mk_table ~eq:CCString.equal 128 in
+  let res = scc ~tbl ~graph (Seq.return "a") |> Seq.to_list in
   assert_bool "scc"
     (set_eq ~eq:(set_eq ?eq:None) res
       [ [ "a"; "b"; "e" ]
@@ -541,8 +545,8 @@ module Dot = struct
 
   (** Print an enum of Full.traverse_event *)
   let pp_seq
-      ?(tbl=mk_table 128)
-      ?(eq=(=))
+      ~tbl
+      ~eq
       ?(attrs_v=fun _ -> [])
       ?(attrs_e=fun _ -> [])
       ?(name="graph")
@@ -598,8 +602,8 @@ module Dot = struct
     Format.fprintf out "}@]@;@?";
     ()
 
-  let pp ?tbl ?eq ?attrs_v ?attrs_e ?name ~graph fmt v =
-    pp_seq ?tbl ?eq ?attrs_v ?attrs_e ?name ~graph fmt (Seq.return v)
+  let pp ~tbl ~eq ?attrs_v ?attrs_e ?name ~graph fmt v =
+    pp_seq ~tbl ~eq ?attrs_v ?attrs_e ?name ~graph fmt (Seq.return v)
 
   let with_out filename f =
     let oc = open_out filename in
@@ -622,7 +626,7 @@ type ('v, 'e) mut_graph = {
   remove : 'v -> unit;
 }
 
-let mk_mut_tbl (type k) ?(eq=(=)) ?(hash=Hashtbl.hash) size =
+let mk_mut_tbl (type k) ~eq ?(hash=Hashtbl.hash) size =
   let module Tbl = Hashtbl.Make(struct
       type t = k
       let hash = hash
@@ -757,7 +761,7 @@ end
 
 (** {2 Misc} *)
 
-let of_list ?(eq=(=)) l =
+let of_list ~eq l =
   (fun v yield -> List.iter (fun (a,b) -> if eq a v then yield ((),b)) l)
 
 let of_fun f =
diff --git a/src/data/CCGraph.mli b/src/data/CCGraph.mli
index 9daa6223..18a34bc6 100644
--- a/src/data/CCGraph.mli
+++ b/src/data/CCGraph.mli
@@ -77,10 +77,10 @@ type ('k, 'a) table = {
 (** Mutable set *)
 type 'a set = ('a, unit) table
 
-val mk_table: ?eq:('k -> 'k -> bool) -> ?hash:('k -> int) -> int -> ('k, 'a) table
+val mk_table: eq:('k -> 'k -> bool) -> ?hash:('k -> int) -> int -> ('k, 'a) table
 (** Default implementation for {!table}: a {!Hashtbl.t} *)
 
-val mk_map: ?cmp:('k -> 'k -> int) -> unit -> ('k, 'a) table
+val mk_map: cmp:('k -> 'k -> int) -> unit -> ('k, 'a) table
 (** Use a {!Map.S} underneath *)
 
 (** {2 Bags of vertices} *)
@@ -104,7 +104,7 @@ val mk_heap: leq:('a -> 'a -> bool) -> 'a bag
 module Traverse : sig
   type ('v, 'e) path = ('v * 'e * 'v) list
 
-  val generic: ?tbl:'v set ->
+  val generic: tbl:'v set ->
     bag:'v bag ->
     graph:('v, 'e) t ->
     'v sequence ->
@@ -120,7 +120,7 @@ module Traverse : sig
     'v sequence_once
   (** One-shot traversal of the graph using a tag set and the given bag *)
 
-  val dfs: ?tbl:'v set ->
+  val dfs: tbl:'v set ->
     graph:('v, 'e) t ->
     'v sequence ->
     'v sequence_once
@@ -130,7 +130,7 @@ module Traverse : sig
     'v sequence ->
     'v sequence_once
 
-  val bfs: ?tbl:'v set ->
+  val bfs: tbl:'v set ->
     graph:('v, 'e) t ->
     'v sequence ->
     'v sequence_once
@@ -140,7 +140,7 @@ module Traverse : sig
     'v sequence ->
     'v sequence_once
 
-  val dijkstra : ?tbl:'v set ->
+  val dijkstra : tbl:'v set ->
     ?dist:('e -> int) ->
     graph:('v, 'e) t ->
     'v sequence ->
@@ -174,15 +174,15 @@ module Traverse : sig
     val get_edge : ('v, 'e) t -> ('v * 'e * 'v) option
     val get_edge_kind : ('v, 'e) t -> ('v * 'e * 'v * edge_kind) option
 
-    val dfs: ?tbl:'v set ->
-      ?eq:('v -> 'v -> bool) ->
+    val dfs: tbl:'v set ->
+      eq:('v -> 'v -> bool) ->
       graph:('v, 'e) graph ->
       'v sequence ->
       ('v,'e) t sequence_once
     (** Full version of DFS.
         @param eq equality predicate on vertices *)
 
-    val dfs_tag: ?eq:('v -> 'v -> bool) ->
+    val dfs_tag: eq:('v -> 'v -> bool) ->
       tags:'v tag_set ->
       graph:('v, 'e) graph ->
       'v sequence ->
@@ -195,7 +195,8 @@ end
 (** {2 Cycles} *)
 
 val is_dag :
-  ?tbl:'v set ->
+  tbl:'v set ->
+  eq:('v -> 'v -> bool) ->
   graph:('v, _) t ->
   'v sequence ->
   bool
@@ -207,9 +208,9 @@ val is_dag :
 
 exception Has_cycle
 
-val topo_sort : ?eq:('v -> 'v -> bool) ->
+val topo_sort : eq:('v -> 'v -> bool) ->
   ?rev:bool ->
-  ?tbl:'v set ->
+  tbl:'v set ->
   graph:('v, 'e) t ->
   'v sequence ->
   'v list
@@ -224,7 +225,7 @@ val topo_sort : ?eq:('v -> 'v -> bool) ->
       [v'] occurs before [v])
     @raise Has_cycle if the graph is not a DAG *)
 
-val topo_sort_tag : ?eq:('v -> 'v -> bool) ->
+val topo_sort_tag : eq:('v -> 'v -> bool) ->
   ?rev:bool ->
   tags:'v tag_set ->
   graph:('v, 'e) t ->
@@ -245,7 +246,7 @@ module Lazy_tree : sig
   val fold_v : ('acc -> 'v -> 'acc) -> 'acc -> ('v, _) t -> 'acc
 end
 
-val spanning_tree : ?tbl:'v set ->
+val spanning_tree : tbl:'v set ->
   graph:('v, 'e) t ->
   'v ->
   ('v, 'e) Lazy_tree.t
@@ -262,7 +263,7 @@ val spanning_tree_tag : tags:'v tag_set ->
 type 'v scc_state
 (** Hidden state for {!scc} *)
 
-val scc : ?tbl:('v, 'v scc_state) table ->
+val scc : tbl:('v, 'v scc_state) table ->
   graph:('v, 'e) t ->
   'v sequence ->
   'v list sequence_once
@@ -304,8 +305,8 @@ module Dot : sig
   type vertex_state
   (** Hidden state associated to a vertex *)
 
-  val pp : ?tbl:('v,vertex_state) table ->
-    ?eq:('v -> 'v -> bool) ->
+  val pp : tbl:('v,vertex_state) table ->
+    eq:('v -> 'v -> bool) ->
     ?attrs_v:('v -> attribute list) ->
     ?attrs_e:('e -> attribute list) ->
     ?name:string ->
@@ -318,8 +319,8 @@ module Dot : sig
       @param attrs_e attributes for edges
       @param name name of the graph *)
 
-  val pp_seq : ?tbl:('v,vertex_state) table ->
-    ?eq:('v -> 'v -> bool) ->
+  val pp_seq : tbl:('v,vertex_state) table ->
+    eq:('v -> 'v -> bool) ->
     ?attrs_v:('v -> attribute list) ->
     ?attrs_e:('e -> attribute list) ->
     ?name:string ->
@@ -340,7 +341,7 @@ type ('v, 'e) mut_graph = {
   remove : 'v -> unit;
 }
 
-val mk_mut_tbl : ?eq:('v -> 'v -> bool) ->
+val mk_mut_tbl : eq:('v -> 'v -> bool) ->
   ?hash:('v -> int) ->
   int ->
   ('v, 'a) mut_graph
@@ -397,7 +398,7 @@ module Map(O : Map.OrderedType) : MAP with type vertex = O.t
 
 (** {2 Misc} *)
 
-val of_list : ?eq:('v -> 'v -> bool) -> ('v * 'v) list -> ('v, unit) t
+val of_list : eq:('v -> 'v -> bool) -> ('v * 'v) list -> ('v, unit) t
 (** [of_list l] makes a graph from a list of pairs of vertices.
     Each pair [(a,b)] is an edge from [a] to [b].
     @param eq equality used to compare vertices *)
diff --git a/src/data/CCHashTrie.ml b/src/data/CCHashTrie.ml
index 926d13c8..8d5c93a0 100644
--- a/src/data/CCHashTrie.ml
+++ b/src/data/CCHashTrie.ml
@@ -24,7 +24,7 @@ module Transient = struct
   type state = { mutable frozen: bool }
   type t = Nil | St of state
   let empty = Nil
-  let equal a b = a==b
+  let equal a b = Pervasives.(==) a b
   let create () = St {frozen=false}
   let active = function Nil -> false | St st -> not st.frozen
   let frozen = function Nil -> true | St st -> st.frozen
@@ -292,13 +292,15 @@ module Make(Key : KEY)
     val make : Key.t -> t
     val zero : t (* special "hash" *)
     val is_0 : t -> bool
+    val equal : t -> t -> bool
     val rem : t -> int (* [A.length_log] last bits *)
     val quotient : t -> t (* remove [A.length_log] last bits *)
   end = struct
     type t = int
     let make = Key.hash
     let zero = 0
-    let is_0 h = h==0
+    let is_0 h = h = 0
+    let equal (a : int) b = Pervasives.(=) a b
     let rem h = h land (A.length - 1)
     let quotient h = h lsr A.length_log
   end
@@ -407,14 +409,14 @@ module Make(Key : KEY)
   let rec add_ ~id k v ~h m = match m with
     | E -> S (h, k, v)
     | S (h', k', v') ->
-      if h=h'
+      if Hash.equal h h'
       then if Key.equal k k'
         then S (h, k, v)  (* replace *)
         else L (h, Cons (k, v, Cons (k', v', Nil)))
       else
         make_array_ ~id ~leaf:(Cons (k', v', Nil)) ~h_leaf:h' k v ~h
     | L (h', l) ->
-      if h=h'
+      if Hash.equal h h'
       then L (h, add_list_ k v l)
       else (* split into N *)
         make_array_ ~id ~leaf:l ~h_leaf:h' k v ~h
diff --git a/src/data/CCIntMap.ml b/src/data/CCIntMap.ml
index cf2e6f82..52b45527 100644
--- a/src/data/CCIntMap.ml
+++ b/src/data/CCIntMap.ml
@@ -11,6 +11,7 @@ module Bit : sig
   type t = private int
   val highest : int -> t
   val min_int : t
+  val equal : t -> t -> bool
   val is_0 : bit:t -> int -> bool
   val is_1 : bit:t -> int -> bool
   val mask : mask:t -> int -> int   (* zeroes the bit, puts all lower bits to 1 *)
@@ -21,6 +22,8 @@ end = struct
 
   let min_int = min_int
 
+  let equal = (=)
+
   let rec highest_bit_naive x m =
     if x=m then m
     else highest_bit_naive (x land (lnot m)) (2*m)
@@ -237,11 +240,11 @@ let update k f t =
 
 let doubleton k1 v1 k2 v2 = add k1 v1 (singleton k2 v2)
 
-let rec equal ~eq a b = a==b || match a, b with
+let rec equal ~eq a b = Pervasives.(==) a b || match a, b with
     | E, E -> true
     | L (ka, va), L (kb, vb) -> ka = kb && eq va vb
     | N (pa, sa, la, ra), N (pb, sb, lb, rb) ->
-      pa=pb && sa=sb && equal ~eq la lb && equal ~eq ra rb
+      pa=pb && Bit.equal sa sb && equal ~eq la lb && equal ~eq ra rb
     | E, _
     | N _, _
     | L _, _ -> false
@@ -287,7 +290,7 @@ let choose t =
   with Not_found -> None
 
 let rec union f t1 t2 =
-  if t1==t2 then t1
+  if Pervasives.(==) t1 t2 then t1
   else match t1, t2 with
     | E, o | o, E -> o
     | L (k, v), o
@@ -295,7 +298,7 @@ let rec union f t1 t2 =
       (* insert k, v into o *)
       insert_ (fun ~old v -> f k old v) k v o
     | N (p1, m1, l1, r1), N (p2, m2, l2, r2) ->
-      if p1 = p2 && m1 = m2
+      if p1 = p2 && Bit.equal m1 m2
       then mk_node_ p1 m1 (union f l1 l2) (union f r1 r2)
       else if Bit.gt m1 m2 && is_prefix_ ~prefix:p1 p2 ~bit:m1
       then if Bit.is_0 p2 ~bit:m1
@@ -342,7 +345,7 @@ let rec union f t1 t2 =
 *)
 
 let rec inter f a b =
-  if a==b then a
+  if Pervasives.(==) a b then a
   else match a, b with
     | E, _ | _, E -> E
     | L (k, v), o
@@ -353,7 +356,7 @@ let rec inter f a b =
         with Not_found -> E
       end
     | N (p1, m1, l1, r1), N (p2, m2, l2, r2) ->
-      if p1 = p2 && m1 = m2
+      if p1 = p2 && Bit.equal m1 m2
       then mk_node_ p1 m1 (inter f l1 l2) (inter f r1 r2)
       else if Bit.gt m1 m2 && is_prefix_ ~prefix:p1 p2 ~bit:m1
       then if Bit.is_0 p2 ~bit:m1
@@ -466,7 +469,7 @@ let compare ~cmp a b =
       then
         let c = cmp va vb in
         if c=0 then cmp_gen cmp a b else c
-      else Pervasives.compare ka kb
+      else compare ka kb
   in
   cmp_gen cmp (to_gen a) (to_gen b)
 
diff --git a/src/data/CCMixmap.ml b/src/data/CCMixmap.ml
index 8c162a36..616aca2b 100644
--- a/src/data/CCMixmap.ml
+++ b/src/data/CCMixmap.ml
@@ -123,9 +123,13 @@ module Make(X : ORD) : S with type key = X.t = struct
 
   let remove = M.remove
 
+  let is_some = function
+    | None -> false
+    | Some _ -> true
+
   let mem ~inj x map =
     try
-      inj.get (M.find x map) <> None
+      is_some (inj.get (M.find x map))
     with Not_found -> false
 
   let iter_keys ~f map =
diff --git a/src/data/CCMixtbl.ml b/src/data/CCMixtbl.ml
index 8d1d9f73..e697a72e 100644
--- a/src/data/CCMixtbl.ml
+++ b/src/data/CCMixtbl.ml
@@ -84,9 +84,13 @@ let remove tbl x = Hashtbl.remove tbl x
 
 let copy tbl = Hashtbl.copy tbl
 
+let is_some = function
+  | None -> false
+  | Some _ -> true
+
 let mem ~inj tbl x =
   try
-    inj.get (Hashtbl.find tbl x) <> None
+    is_some (inj.get (Hashtbl.find tbl x))
   with Not_found -> false
 
 (*$R
diff --git a/src/data/CCMultiSet.ml b/src/data/CCMultiSet.ml
index 39d13019..9e9a01cb 100644
--- a/src/data/CCMultiSet.ml
+++ b/src/data/CCMultiSet.ml
@@ -5,6 +5,9 @@
 
 type 'a sequence = ('a -> unit) -> unit
 
+let max_int = max
+let min_int = min
+
 module type S = sig
   type elt
   type t
@@ -172,7 +175,7 @@ module Make(O : Set.OrderedType) = struct
       (fun _ n1 n2 -> match n1, n2 with
          | None, None -> assert false
          | Some n, None | None, Some n -> Some n
-         | Some n1, Some n2 -> Some (Pervasives.max n1 n2))
+         | Some n1, Some n2 -> Some (max_int n1 n2))
       m1 m2
 
   let intersection m1 m2 =
@@ -181,7 +184,7 @@ module Make(O : Set.OrderedType) = struct
          | None, None -> assert false
          | Some _, None
          | None, Some _ -> None
-         | Some n1, Some n2 -> Some (Pervasives.min n1 n2))
+         | Some n1, Some n2 -> Some (min_int n1 n2))
       m1 m2
 
   let diff m1 m2 =
diff --git a/src/data/CCRAL.ml b/src/data/CCRAL.ml
index 5d9aa245..e540b755 100644
--- a/src/data/CCRAL.ml
+++ b/src/data/CCRAL.ml
@@ -96,7 +96,7 @@ let tl l = match l with
 (*$Q
   Q.(list_of_size Gen.(1--100) int) (fun l -> \
     let l' =  of_list l in \
-    (not (is_empty l')) ==> (equal l' (cons (hd l') (tl l'))) )
+    (not (is_empty l')) ==> (equal ~eq:CCInt.equal l' (cons (hd l') (tl l'))) )
 *)
 
 let front l = match l with
@@ -371,7 +371,7 @@ let drop_while ~f l =
 
 let take_drop n l = take n l, drop n l
 
-let equal ?(eq=(=)) l1 l2 =
+let equal ~eq l1 l2 =
   let rec aux ~eq l1 l2 = match l1, l2 with
     | Nil, Nil -> true
     | Cons (size1, t1, l1'), Cons (size2, t2, l2') ->
@@ -389,7 +389,7 @@ let equal ?(eq=(=)) l1 l2 =
 
 (*$Q
   Q.(pair (list int)(list int)) (fun (l1,l2) -> \
-    equal (of_list l1) (of_list l2) = (l1=l2))
+    equal ~eq:CCInt.equal (of_list l1) (of_list l2) = (l1=l2))
 *)
 
 (** {2 Utils} *)
@@ -543,7 +543,7 @@ let rec of_list_map ~f l = match l with
     let y = f x in
     cons y (of_list_map ~f l')
 
-let compare ?(cmp=Pervasives.compare) l1 l2 =
+let compare ~cmp l1 l2 =
   let rec cmp_gen ~cmp g1 g2 = match g1(), g2() with
     | None, None -> 0
     | Some _, None -> 1
@@ -556,7 +556,7 @@ let compare ?(cmp=Pervasives.compare) l1 l2 =
 
 (*$Q
   Q.(pair (list int)(list int)) (fun (l1,l2) -> \
-    compare (of_list l1) (of_list l2) = (Pervasives.compare l1 l2))
+    compare ~cmp:CCInt.compare (of_list l1) (of_list l2) = (Pervasives.compare l1 l2))
 *)
 
 (** {2 Infix} *)
diff --git a/src/data/CCRAL.mli b/src/data/CCRAL.mli
index 0e76eca3..70f7f12b 100644
--- a/src/data/CCRAL.mli
+++ b/src/data/CCRAL.mli
@@ -109,9 +109,9 @@ val rev_map : f:('a -> 'b) -> 'a t -> 'b t
 val rev : 'a t -> 'a t
 (** Reverse the list *)
 
-val equal : ?eq:('a -> 'a -> bool) -> 'a t -> 'a t -> bool
+val equal : eq:('a -> 'a -> bool) -> 'a t -> 'a t -> bool
 
-val compare : ?cmp:('a -> 'a -> int) -> 'a t -> 'a t -> int
+val compare : cmp:('a -> 'a -> int) -> 'a t -> 'a t -> int
 (** Lexicographic comparison *)
 
 (** {2 Utils} *)
diff --git a/src/data/CCSimple_queue.ml b/src/data/CCSimple_queue.ml
index ed9b639c..1eea0162 100644
--- a/src/data/CCSimple_queue.ml
+++ b/src/data/CCSimple_queue.ml
@@ -23,7 +23,11 @@ let make_ hd tl = match hd with
   | [] -> {hd=List.rev tl; tl=[] }
   | _::_ -> {hd; tl; }
 
-let is_empty q = q.hd = []
+let list_is_empty = function
+  | [] -> true
+  | _::_ -> false
+
+let is_empty q = list_is_empty q.hd
 
 let push x q = make_ q.hd (x :: q.tl)
 
@@ -31,7 +35,7 @@ let snoc q x = push x q
 
 let peek_exn q =
   match q.hd with
-    | [] -> assert (q.tl = []); invalid_arg "Queue.peek"
+    | [] -> assert (list_is_empty q.tl); invalid_arg "Queue.peek"
     | x::_ -> x
 
 let peek q = match q.hd with
@@ -40,7 +44,7 @@ let peek q = match q.hd with
 
 let pop_exn q =
   match q.hd with
-    | [] -> assert (q.tl = []); invalid_arg "Queue.peek"
+    | [] -> assert (list_is_empty q.tl); invalid_arg "Queue.peek"
     | x::hd' ->
       let q' = make_ hd' q.tl in
       x, q'
diff --git a/src/data/CCTrie.ml b/src/data/CCTrie.ml
index d7f8b9f7..c5beeae7 100644
--- a/src/data/CCTrie.ml
+++ b/src/data/CCTrie.ml
@@ -527,7 +527,7 @@ module Make(W : WORD)
     | Empty -> 0
     | Cons (_, t') -> size t'
     | Node (v, map) ->
-      let s = if v=None then 0 else 1 in
+      let s = match v with None -> 0 | Some _ -> 1 in
       M.fold
         (fun _ t' acc -> size t' + acc)
         map s
diff --git a/src/iter/CCKList.ml b/src/iter/CCKList.ml
index 13b0ae44..28be96a6 100644
--- a/src/iter/CCKList.ml
+++ b/src/iter/CCKList.ml
@@ -422,11 +422,11 @@ let of_gen g =
   assert_equal [11;12] (drop 10 l |> take 2 |> to_list);
 *)
 
-let sort ?(cmp=Pervasives.compare) l =
+let sort ~cmp l =
   let l = to_list l in
   of_list (List.sort cmp l)
 
-let sort_uniq ?(cmp=Pervasives.compare) l =
+let sort_uniq ~cmp l =
   let l = to_list l in
   uniq (fun x y -> cmp x y = 0) (of_list (List.sort cmp l))
 
diff --git a/src/iter/CCKList.mli b/src/iter/CCKList.mli
index e304138d..8c027470 100644
--- a/src/iter/CCKList.mli
+++ b/src/iter/CCKList.mli
@@ -164,12 +164,12 @@ val unzip : ('a * 'b) t -> 'a t * 'b t
 
 (** {2 Misc} *)
 
-val sort : ?cmp:'a ord -> 'a t -> 'a t
+val sort : cmp:'a ord -> 'a t -> 'a t
 (** Eager sort. Requires the iterator to be finite. O(n ln(n)) time
     and space.
     @since 0.3.3 *)
 
-val sort_uniq : ?cmp:'a ord -> 'a t -> 'a t
+val sort_uniq : cmp:'a ord -> 'a t -> 'a t
 (** Eager sort that removes duplicate values. Requires the iterator to be
     finite. O(n ln(n)) time and space.
     @since 0.3.3 *)
diff --git a/src/iter/CCKTree.ml b/src/iter/CCKTree.ml
index eae5a29c..2e041847 100644
--- a/src/iter/CCKTree.ml
+++ b/src/iter/CCKTree.ml
@@ -91,7 +91,7 @@ class type ['a] pset = object
   method mem : 'a -> bool
 end
 
-let set_of_cmp (type elt) ?(cmp=Pervasives.compare) () =
+let set_of_cmp (type elt) ~cmp () =
   let module S = Set.Make(struct
       type t = elt
       let compare = cmp
@@ -105,7 +105,7 @@ let set_of_cmp (type elt) ?(cmp=Pervasives.compare) () =
 let _nil () = `Nil
 let _cons x l = `Cons (x, l)
 
-let dfs ?(pset=set_of_cmp ()) t =
+let dfs ~pset t =
   let rec dfs pset stack () = match stack with
     | [] -> `Nil
     | `Explore t :: stack' ->
@@ -141,19 +141,23 @@ module FQ = struct
 
   let empty = _make [] []
 
-  let is_empty q = q.hd = []
+  let list_is_empty = function
+    | [] -> true
+    | _::_ -> false
+
+  let is_empty q = list_is_empty q.hd
 
   let push q x = _make q.hd (x::q.tl)
 
   let pop_exn q =
     match q.hd with
-      | [] -> assert (q.tl = []); raise Empty
+      | [] -> assert (list_is_empty q.tl); raise Empty
       | x::hd' ->
         let q' = _make hd' q.tl in
         x, q'
 end
 
-let bfs ?(pset=set_of_cmp ()) t =
+let bfs ~pset t =
   let rec bfs pset q () =
     if FQ.is_empty q then `Nil
     else
@@ -173,7 +177,7 @@ let rec force t : ([`Nil | `Node of 'a * 'b list] as 'b) = match t() with
   | `Nil -> `Nil
   | `Node (x, l) -> `Node (x, List.map force l)
 
-let find ?pset f t =
+let find ~pset f t =
   let rec _find_kl f l = match l() with
     | `Nil -> None
     | `Cons (x, l') ->
@@ -181,7 +185,7 @@ let find ?pset f t =
         | None -> _find_kl f l'
         | Some _ as res -> res
   in
-  _find_kl f (bfs ?pset t)
+  _find_kl f (bfs ~pset t)
 
 (** {2 Pretty-printing} *)
 
diff --git a/src/iter/CCKTree.mli b/src/iter/CCKTree.mli
index fadf711c..9ef94fdd 100644
--- a/src/iter/CCKTree.mli
+++ b/src/iter/CCKTree.mli
@@ -80,13 +80,13 @@ class type ['a] pset = object
   method mem : 'a -> bool
 end
 
-val set_of_cmp : ?cmp:('a -> 'a -> int) -> unit -> 'a pset
+val set_of_cmp : cmp:('a -> 'a -> int) -> unit -> 'a pset
 (** Build a set structure given a total ordering *)
 
-val dfs : ?pset:'a pset -> 'a t -> [ `Enter of 'a | `Exit of 'a ] klist
+val dfs : pset:'a pset -> 'a t -> [ `Enter of 'a | `Exit of 'a ] klist
 (** Depth-first traversal of the tree *)
 
-val bfs : ?pset:'a pset -> 'a t -> 'a klist
+val bfs : pset:'a pset -> 'a t -> 'a klist
 (** Breadth-first traversal of the tree *)
 
 val force : 'a t -> ([ `Nil | `Node of 'a * 'b list ] as 'b)
@@ -94,7 +94,7 @@ val force : 'a t -> ([ `Nil | `Node of 'a * 'b list ] as 'b)
     structure
     @since 0.13 *)
 
-val find : ?pset:'a pset -> ('a -> 'b option) -> 'a t -> 'b option
+val find : pset:'a pset -> ('a -> 'b option) -> 'a t -> 'b option
 (** Look for an element that maps to [Some _] *)
 
 (** {2 Pretty-printing}
diff --git a/src/monomorphic/CCMonomorphic.ml b/src/monomorphic/CCMonomorphic.ml
new file mode 100644
index 00000000..3817b80a
--- /dev/null
+++ b/src/monomorphic/CCMonomorphic.ml
@@ -0,0 +1,6 @@
+
+(* This file is free software, part of containers. See file "license" for more details. *)
+
+include Pervasives
+
+let (==) = `Consider_using_CCEqual_physical
diff --git a/src/monomorphic/CCMonomorphic.mli b/src/monomorphic/CCMonomorphic.mli
new file mode 100644
index 00000000..d11e1514
--- /dev/null
+++ b/src/monomorphic/CCMonomorphic.mli
@@ -0,0 +1,19 @@
+
+(* This file is free software, part of containers. See file "license" for more details. *)
+
+(** {1 Shadow unsafe functions and operators from Pervasives} *)
+(** @since NEXT_RELEASE *)
+
+val (=) : int -> int -> bool
+val (<>) : int -> int -> bool
+val (<) : int -> int -> bool
+val (>) : int -> int -> bool
+val (<=) : int -> int -> bool
+val (>=) : int -> int -> bool
+
+val compare : int -> int -> int
+val min : int -> int -> int
+val max : int -> int -> int
+
+val (==) : [`Consider_using_CCEqual_physical]
+[@@ocaml.deprecated "Please use CCEqual.physical or Pervasives.(==) instead."]
diff --git a/src/sexp/CCSexp.ml b/src/sexp/CCSexp.ml
index 6e5d96a0..25857c31 100644
--- a/src/sexp/CCSexp.ml
+++ b/src/sexp/CCSexp.ml
@@ -13,9 +13,32 @@ type t = [
 ]
 type sexp = t
 
-let equal a b = a = b
+let equal_string (a : string) b = Pervasives.(=) a b
 
-let compare a b = Pervasives.compare a b
+let rec equal a b = match a, b with
+  | `Atom s1, `Atom s2 ->
+    equal_string s1 s2
+  | `List l1, `List l2 ->
+    begin try List.for_all2 equal l1 l2 with Invalid_argument _ -> false end
+  | `Atom _, _ | `List _, _ -> false
+
+let compare_string (a : string) b = Pervasives.compare a b
+
+let rec compare_list a b = match a, b with
+  | [], [] -> 0
+  | [], _::_ -> -1
+  | _::_, [] -> 1
+  | x::xs, y::ys ->
+    begin match compare x y with
+      | 0 -> compare_list xs ys
+      | c -> c
+    end
+
+and compare a b = match a, b with
+  | `Atom s1, `Atom s2 -> compare_string s1 s2
+  | `List l1, `List l2 -> compare_list l1 l2
+  | `Atom _, _ -> -1
+  | `List _, _ -> 1
 
 let hash a = Hashtbl.hash a
 
diff --git a/src/sexp/CCSexp_lex.mll b/src/sexp/CCSexp_lex.mll
index c67e66eb..024d0a6b 100644
--- a/src/sexp/CCSexp_lex.mll
+++ b/src/sexp/CCSexp_lex.mll
@@ -20,9 +20,11 @@
     | Escaped_int_1 of int
     | Escaped_int_2 of int
 
+  let char_equal (a : char) b = Pervasives.(=) a b
+
   (* remove quotes + unescape *)
   let remove_quotes lexbuf s =
-    assert (s.[0] = '"' && s.[String.length s - 1] = '"');
+    assert (char_equal s.[0] '"' && char_equal s.[String.length s - 1] '"');
     let buf = Buffer.create (String.length s) in
     let st = ref Not_escaped in
     for i = 1 to String.length s-2 do
@@ -72,4 +74,3 @@ rule token = parse
   | string { ATOM (remove_quotes lexbuf (Lexing.lexeme lexbuf)) }
   | _ as c
     { error lexbuf (Printf.sprintf "lexing failed on char `%c`" c) }
-
diff --git a/src/threads/CCPool.ml b/src/threads/CCPool.ml
index 914461cc..af8ab6ba 100644
--- a/src/threads/CCPool.ml
+++ b/src/threads/CCPool.ml
@@ -314,11 +314,15 @@ module Make(P : PARAM) = struct
       | Run cell ->
         with_lock_ cell (fun cell -> cell.state)
 
+    let is_not_waiting = function
+      | Waiting -> false
+      | Failed _ | Done _ -> true
+
     let is_done = function
       | Return _
       | FailNow _ -> true
       | Run cell ->
-        with_lock_ cell (fun c -> c.state <> Waiting)
+        with_lock_ cell (fun c -> is_not_waiting c.state)
 
     (** {2 Combinators *)
 
diff --git a/src/threads/CCTimer.ml b/src/threads/CCTimer.ml
index f2c37cb8..9ad6e2c4 100644
--- a/src/threads/CCTimer.ml
+++ b/src/threads/CCTimer.ml
@@ -6,6 +6,11 @@
 type job =
   | Job : float * (unit -> 'a) -> job
 
+let (<=) (a : float) b = Pervasives.(<=) a b
+let (>=) (a : float) b = Pervasives.(>=) a b
+let (<) (a : float) b = Pervasives.(<) a b
+let (>) (a : float) b = Pervasives.(>) a b
+
 module TaskHeap = CCHeap.Make(struct
     type t = job
     let leq (Job(f1,_)) (Job (f2,_)) = f1 <= f2