package fmlib

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in-package search v0.2.0

Functional monadic library

Install

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Optional elements of a certain type.

type 'a t = 'a option

'a t Type of an optional object of type 'a

val return : 'a -> 'a t

return a Equivalent to Some a.

val fail : 'a t

Equivalent to None.

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

Chaining of operations which return optional elements.

Example:

    let* a = op1 ... in (* 'op1 ... ' returns an optional element *)
    let* b = op2 ... in
    let* c = op3 ... in
    ...
    return (f a b c ...)

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

opt >>= f Equivalent to let* v = opt in f v.

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

map f m Map the element of m by f, if exists.

val to_list : 'a t -> 'a list

to_list a Returns a one element list or an empty list.