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https://github.com/c-cube/ocaml-containers.git
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new combinators for CCIO
This commit is contained in:
Simon Cruanes
parent
a913b6f1c0
commit
b88461d834
2 changed files with 179 additions and 7 deletions
131
core/CCIO.ml
131
core/CCIO.ml
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@ -28,19 +28,26 @@ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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type _ t =
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| Return : 'a -> 'a t
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| Fail : string -> 'a t
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| Map : ('a -> 'b) * 'a t -> 'b t
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| Bind : ('a -> 'b t) * 'a t -> 'b t
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| BindWith : unit t * ('a -> 'b t) * 'a t -> 'b t
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| Star : ('a -> 'b) t * 'a t -> 'b t
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| Repeat : int * 'a t -> 'a list t
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| RepeatIgnore : int * 'a t -> unit t
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| Wrap : (unit -> 'a) -> 'a t
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| WrapJoin : (unit -> 'a t) -> 'a t
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| SequenceMap : ('a -> 'b t) * 'a list -> 'b list t
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type 'a io = 'a t
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type 'a or_error = [ `Ok of 'a | `Error of string ]
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let (>>=) x f = Bind(f,x)
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let bind ?finalize f a = match finalize with
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| None -> Bind(f,a)
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| Some b -> BindWith (b,f,a)
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let map f x = Map(f, x)
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let (>|=) x f = Map(f, x)
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@ -48,6 +55,8 @@ let (>|=) x f = Map(f, x)
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let return x = Return x
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let pure = return
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let fail msg = Fail msg
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let (<*>) f a = Star (f, a)
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let lift = map
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@ -59,37 +68,69 @@ let lift3 f a b c =
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a >>= fun x ->
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b >>= fun y -> map (f x y) c
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let sequence_map f l =
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SequenceMap (f,l)
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let sequence l =
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let _id x = x in
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SequenceMap(_id, l)
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let repeat i a =
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if i <= 0 then Return [] else Repeat (i,a)
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let repeat' i a =
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if i <= 0 then Return () else RepeatIgnore (i,a)
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exception IOFailure of string
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let rec _run : type a. a t -> a = function
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| Return x -> x
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| Fail msg -> raise (IOFailure msg)
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| Map (f, a) -> f (_run a)
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| Bind (f, a) -> _run (f (_run a))
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| BindWith (finalize, f, a) ->
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begin try
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let res = _run (f (_run a)) in
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_run finalize;
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res
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with e ->
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_run finalize;
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raise e
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end
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| Star (f, a) -> _run f (_run a)
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| Repeat (i,a) -> _repeat [] i a
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| RepeatIgnore (i,a) -> _repeat_ignore i a
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| Wrap f -> f()
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| WrapJoin f -> _run (f())
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| SequenceMap (f, l) -> _sequence_map f l []
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and _repeat : type a. a list -> int -> a t -> a list
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= fun acc i a -> match i with
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| 0 -> List.rev acc
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| _ ->
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let x = _run a in
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_repeat (x::acc) (i-1) a
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and _repeat_ignore : type a. int -> a t -> unit
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= fun i a -> match i with
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| 0 -> ()
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| _ ->
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let _ = _run a in
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_repeat_ignore (i-1) a
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let _printers = ref []
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and _sequence_map : type a b. (a -> b t) -> a list -> b list -> b list
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= fun f l acc -> match l with
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| [] -> List.rev acc
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| a::tail ->
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let x = _run (f a) in
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_sequence_map f tail (x::acc)
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let _printers =
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ref [
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(* default printer *)
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( function IOFailure msg
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| Sys_error msg -> Some msg
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| Exit -> Some "exit"
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| _ -> None
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)
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]
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exception PrinterResult of string
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@ -107,6 +148,12 @@ let run x =
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try `Ok (_run x)
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with e -> `Error (_print_exn e)
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exception IO_error of string
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let run_exn x =
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try _run x
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with e -> raise (IO_error (_print_exn e))
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let register_printer p = _printers := p :: !_printers
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(** {2 Standard Wrappers} *)
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@ -125,9 +172,30 @@ let with_in ?(flags=[]) filename f =
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let _read ic s i len () = input ic s i len
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let read ic s i len = Wrap (_read ic s i len)
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let _read_line ic () = Pervasives.input_line ic
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let _read_line ic () =
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try Some (Pervasives.input_line ic)
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with End_of_file -> None
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let read_line ic = Wrap(_read_line ic)
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let rec _read_lines ic acc =
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read_line ic
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>>= function
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| None -> return (List.rev acc)
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| Some l -> _read_lines ic (l::acc)
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let read_lines ic = _read_lines ic []
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let _read_all ic () =
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let buf = Buffer.create 128 in
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try
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while true do
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Buffer.add_channel buf ic 1024
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done;
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"" (* never returned *)
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with End_of_file -> Buffer.contents buf
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let read_all ic = Wrap(_read_all ic)
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let _with_out flags filename f () =
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let oc = open_out_gen flags 0x644 filename in
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try
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@ -145,6 +213,11 @@ let write oc s i len = Wrap (_write oc s i len)
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let _write_str oc s () = output oc s 0 (String.length s)
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let write_str oc s = Wrap (_write_str oc s)
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let _write_line oc l () =
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output_string oc l;
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output_char oc '\n'
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let write_line oc l = Wrap (_write_line oc l)
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let _write_buf oc buf () = Buffer.output_buffer oc buf
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let write_buf oc buf = Wrap (_write_buf oc buf)
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@ -208,6 +281,22 @@ module Seq = struct
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in
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_next
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(* apply all actions from [l] to [x] *)
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let rec _apply_all_to x l = match l with
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| [] -> return ()
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| f::tail -> f x >>= fun () -> _apply_all_to x tail
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let _tee funs g () =
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g() >>= function
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| Stop -> _stop()
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| Yield x ->
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_apply_all_to x funs >>= fun () ->
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_yield x
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let tee funs g = match funs with
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| [] -> g
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| _::_ -> _tee funs g
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(** {6 Consume} *)
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let rec fold_pure f acc g =
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@ -230,10 +319,42 @@ module Seq = struct
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let of_fun g = g
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(* TODO: wrapper around with_in? using bind ~finalize:... ? *)
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let chunks ~size ic =
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let buf = Buffer.create size in
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let next() =
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try
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Buffer.add_channel buf ic size;
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let s = Buffer.contents buf in
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Buffer.clear buf;
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_yield s
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with End_of_file -> _stop()
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in
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next
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let lines ic () =
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try _yield (input_line ic)
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with End_of_file -> _stop()
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let words g =
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failwith "words: not implemented yet"
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(* TODO: state machine that goes:
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- 0: read input chunk
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- switch to "search for ' '", and yield word
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- goto 0 if no ' ' found
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- yield leftover when g returns Stop
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let buf = Buffer.create 32 in
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let next() =
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g() >>= function
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| Stop -> _stop
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| Yield s ->
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Buffer.add_string buf s;
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search_
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in
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next
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*)
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let output ?(sep="\n") oc seq =
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let first = ref true in
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iter
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@ -24,7 +24,12 @@ OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*)
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(** {1 IO Monad} *)
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(** {1 IO Monad}
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A simple abstraction over blocking IO, with strict evaluation. This is in
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no way an alternative to Lwt/Async if you need concurrency.
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@since NEXT_RELEASE *)
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type 'a t
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type 'a io = 'a t
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@ -49,6 +54,13 @@ val map : ('a -> 'b) -> 'a t -> 'b t
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val (>|=) : 'a t -> ('a -> 'b) -> 'b t
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val bind : ?finalize:(unit t) -> ('a -> 'b t) -> 'a t -> 'b t
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(** [bind f a] runs the action [a] and applies [f] to its result
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to obtain a new action. It then behaves exactly like this new
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action.
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@param finalize an optional action that is always run after evaluating
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the whole action *)
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val pure : 'a -> 'a t
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val (<*>) : ('a -> 'b) t -> 'a t -> 'b t
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@ -58,11 +70,27 @@ val lift : ('a -> 'b) -> 'a t -> 'b t
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val lift2 : ('a -> 'b -> 'c) -> 'a t -> 'b t -> 'c t
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val lift3 : ('a -> 'b -> 'c -> 'd) -> 'a t -> 'b t -> 'c t -> 'd t
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val sequence : 'a t list -> 'a list t
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(** Runs operations one by one and gather their results *)
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val sequence_map : ('a -> 'b t) -> 'a list -> 'b list t
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(** Generalization of {!sequence} *)
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val fail : string -> 'a t
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(** [fail msg] fails with the given message. Running the IO value will
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return an [`Error] variant *)
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val run : 'a t -> 'a or_error
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(** Run an IO action.
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@return either [`Ok x] when [x] is the successful result of the
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computation, or some [`Error "message"] *)
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exception IO_error of string
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val run_exn : 'a t -> 'a
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(** Unsafe version of {!run}. It assumes non-failure.
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@raise IO_error if the execution didn't go well *)
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val register_printer : (exn -> string option) -> unit
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(** [register_printer p] register [p] as a possible failure printer.
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If [run a] raises an exception [e], [p e] is evaluated. If [p e = Some msg]
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@ -76,8 +104,16 @@ val register_printer : (exn -> string option) -> unit
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val with_in : ?flags:open_flag list -> string -> (in_channel -> 'a t) -> 'a t
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val read : in_channel -> string -> int -> int -> int t
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(** Read a chunk into the given string *)
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val read_line : in_channel -> string t
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val read_line : in_channel -> string option t
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(** Read a line from the channel. Returns [None] if the input is terminated. *)
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val read_lines : in_channel -> string list t
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(** Read all lines eagerly *)
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val read_all : in_channel -> string t
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(** Read the whole channel into a buffer, then converted into a string *)
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(** {6 Output} *)
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@ -89,8 +125,12 @@ val write_str : out_channel -> string -> unit t
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val write_buf : out_channel -> Buffer.t -> unit t
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val write_line : out_channel -> string -> unit t
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val flush : out_channel -> unit t
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(* TODO: printf/fprintf wrappers *)
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(** {2 Streams} *)
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module Seq : sig
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@ -117,6 +157,11 @@ module Seq : sig
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[c] an optional output value.
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The result is the stream of values output by [f] *)
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val tee : ('a -> unit io) list -> 'a t -> 'a t
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(** [tee funs seq] behaves like [seq], but each element is given to
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every function [f] in [funs]. This function [f] returns an action that
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is eagerly executed. *)
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(** {6 Consume} *)
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val iter : ('a -> _ io) -> 'a t -> unit io
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@ -143,9 +188,15 @@ module Seq : sig
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val of_fun : 'a gen -> 'a t
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(** Create a stream from a function that yields an element or stops *)
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val chunks : size:int -> in_channel -> string t
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(** Read the channel's content into chunks of size [size] *)
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val lines : in_channel -> string t
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(** Lines of an input channel *)
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val words : string t -> string t
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(** Split strings into words at " " boundaries *)
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val output : ?sep:string -> out_channel -> string t -> unit io
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(** [output oc seq] outputs every value of [seq] into [oc], separated
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with the optional argument [sep] (default: ["\n"]) *)
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