monads

A missing monad library
IN THIS PACKAGE
Parameter #1 Monads . Std . Monad . State . Make2 . M
type 'a t
val void : 'a t -> unit t

void m computes m and discrards the result.

val sequence : unit t list -> unit t

sequence xs computes a sequence of computations xs in the left to right order.

val forever : 'a t -> 'b t

forever xs creates a computationt that never returns.

module Fn : sig ... end

Various function combinators lifted into the Kleisli category.

module Pair : sig ... end

The pair interface lifted into the monad.

module Triple : sig ... end

The triple interface lifted into a monad.

module Lift : sig ... end

Lifts functions into the monad.

module Exn : sig ... end

Interacting between monads and language exceptions

module Collection : sig ... end

Lifts collection interface into the monad.

module List : Collection.S with type 'a t := 'a list

The Monad.Collection.S interface for lists

module Seq : Collection.S with type 'a t := 'a Core_kernel.Sequence.t

The Monad.Collection.S interface for sequences

include Syntax.S with type 'a t := 'a t
val (>>=) : 'a t -> ( 'a -> 'b t ) -> 'b t

m >>= f is bind m f

val (>>|) : 'a t -> ( 'a -> 'b ) -> 'b t

m >>= f is map m ~f

val (>=>) : ( 'a -> 'b t ) -> ( 'b -> 'c t ) -> 'a -> 'c t

f >=> g is fun x -> f x >>= g

val (!!) : 'a -> 'a t

!!x is return x

val (!$) : ( 'a -> 'b ) -> 'a t -> 'b t

!$f is Lift.unary f

val (!$$) : ( 'a -> 'b -> 'c ) -> 'a t -> 'b t -> 'c t

!$$f is Lift.binary f

val (!$$$) : ( 'a -> 'b -> 'c -> 'd ) -> 'a t -> 'b t -> 'c t -> 'd t

!$$$f is Lift.ternary f

val (!$$$$) : ( 'a -> 'b -> 'c -> 'd -> 'e ) -> 'a t -> 'b t -> 'c t -> 'd t -> 'e t

!$$$$f is Lift.quaternary f

val (!$$$$$) : ( 'a -> 'b -> 'c -> 'd -> 'e -> 'f ) -> 'a t -> 'b t -> 'c t -> 'd t -> 'e t -> 'f t

!$$$$$f is Lift.quinary f

include Syntax.Let.S with type 'a t := 'a t
val let* : 'a t -> ( 'a -> 'b t ) -> 'b t

let* r = f x in b is f x >>= fun r -> b

val and* : 'a t -> 'b t -> ('a * 'b) t

monoidal product

val let+ : 'a t -> ( 'a -> 'b ) -> 'b t

let+ r = f x in b is f x >>| fun r -> b

val and+ : 'a t -> 'b t -> ('a * 'b) t

monoidal product

include Core_kernel.Monad.S with type 'a t := 'a t
val (>>=) : 'a t -> ( 'a -> 'b t ) -> 'b t

t >>= f returns a computation that sequences the computations represented by two monad elements. The resulting computation first does t to yield a value v, and then runs the computation returned by f v.

val (>>|) : 'a t -> ( 'a -> 'b ) -> 'b t

t >>| f is t >>= (fun a -> return (f a)).

module Monad_infix : sig ... end
val bind : 'a t -> f:( 'a -> 'b t ) -> 'b t

bind t ~f = t >>= f

val return : 'a -> 'a t

return v returns the (trivial) computation that returns v.

val map : 'a t -> f:( 'a -> 'b ) -> 'b t

map t ~f is t >>| f.

val join : 'a t t -> 'a t

join t is t >>= (fun t' -> t').

val ignore_m : 'a t -> unit t

ignore_m t is map t ~f:(fun _ -> ()). ignore_m used to be called ignore, but we decided that was a bad name, because it shadowed the widely used Caml.ignore. Some monads still do let ignore = ignore_m for historical reasons.

val all : 'a t list -> 'a list t
val all_unit : unit t list -> unit t

Like all, but ensures that every monadic value in the list produces a unit value, all of which are discarded rather than being collected into a list.

module Let_syntax : sig ... end

These are convenient to have in scope when programming with a monad:

module Let : Syntax.Let.S with type 'a t := 'a t

Monadic operators, see Monad.Syntax.S for more.

module Syntax : Syntax.S with type 'a t := 'a t

Monadic operators, see Monad.Syntax.S for more.