ResultMonad (tmpl_dcr.Common.Monads.ResultMonad)

ResultMonad

An implementation of a monad "design pattern" for handling errors across functions, using the Result type.

val return : ?map_ok:('a -> 'a) -> 'a -> ('a, 'b) Stdlib.result

return ?map_ok x wraps the value x in an Ok result. If map_ok is provided, it applies the function f to x before wrapping it.

parameter map_ok
a function to apply to the value before wrapping it in Ok.

parameter x
the value to wrap.

returns
the value x wrapped in an Ok result.

val fail : ?map_error:('a -> 'a) -> 'a -> ('b, 'a) Stdlib.result

fail ?map_error e wraps the value e in an Error result. If map_error is provided, it applies the function f to e before wrapping it in Error.

parameter map_error
a function to apply to the value before wrapping it in Error.

parameter e
the value to wrap in Error.

returns
the value e wrapped in an Error result.

val bind : 
  ('a, 'b) Stdlib.result ->
  ('a -> ('c, 'b) Stdlib.result) ->
  ('c, 'b) Stdlib.result

bind m f applies the function f to the value inside m if m is Ok, otherwise returns the same Error value. Note: This function doesn't accumulate errors.

parameter m
the result to bind.

parameter f
the function to apply to the value inside m.

returns
the result of applying f to the value inside m.

val (>>=) : 
  ('a, 'b) Stdlib.result ->
  ('a -> ('c, 'b) Stdlib.result) ->
  ('c, 'b) Stdlib.result

( >>= ) m f is an infix operator for bind.

val let* : 
  ('a, 'b) Stdlib.result ->
  ('a -> ('c, 'b) Stdlib.result) ->
  ('c, 'b) Stdlib.result

( let* ) m f is a syntactic sugar for bind in monadic let binding.

val apply : ('a, 'b) Stdlib.result -> ('a -> 'c) -> ('c, 'b) Stdlib.result

apply m f applies the function f to the value inside m if m is Ok, and wraps the result in Ok.

parameter m
the result to apply the function to.

parameter f
the function to apply to the value inside m.

returns
the result of applying f to the value inside m.

val (>>|) : ('a, 'b) Stdlib.result -> ('a -> 'c) -> ('c, 'b) Stdlib.result

( >>| ) m f is an infix operator for apply.

val let+ : ('a, 'b) Stdlib.result -> ('a -> 'c) -> ('c, 'b) Stdlib.result

( let+ ) m f is a syntactic sugar for apply in monadic let binding.

val compose : 
  ('a, 'b) Stdlib.result ->
  ('a -> ('c, 'b) Stdlib.result) ->
  ('c -> ('d, 'b) Stdlib.result) ->
  ('d, 'b) Stdlib.result

val (>=>) : 
  ('a, 'b) Stdlib.result ->
  ('a -> ('c, 'b) Stdlib.result) ->
  ('c -> ('d, 'b) Stdlib.result) ->
  ('d, 'b) Stdlib.result

val bind_error : 
  ('a, 'b) Stdlib.result ->
  ('b -> ('a, 'c) Stdlib.result) ->
  ('a, 'c) Stdlib.result

bind_error m f applies the function f to the value inside m if m is Error, otherwise returns the Ok value.

parameter m
the result to bind.

parameter f
the function to apply to the value inside m.

returns
the result of applying f to the value inside m.

val (>>!) : 
  ('a, 'b) Stdlib.result ->
  ('b -> ('a, 'c) Stdlib.result) ->
  ('a, 'c) Stdlib.result

( >>! ) m f is an infix operator for bind_error.

val fold_left : 
  ('a -> 'b -> ('a, 'c) Stdlib.result) ->
  'a ->
  'b list ->
  ('a, 'c) Stdlib.result

fold_left f acc l is a monadic fold left over the list l with the function f, threading an accumulator of type result.

parameter f
the function to fold with.

parameter acc
the initial accumulator.

parameter l
the list to fold over.

returns
the result of folding over the list l.

val fold_left2 : 
  ('a -> 'b -> 'c -> ('a, 'd) Stdlib.result) ->
  'a ->
  'b list ->
  'c list ->
  ('a, 'd) Stdlib.result

fold_left2 f acc l1 l2 folds the lists l1 and l2 from the left with the function f, threading an accumulator of type result.

parameter f
the function to fold with.

parameter acc
the initial accumulator.

parameter l1
the first list to fold over.

parameter l2
the second list to fold over.

returns
the result of folding over the lists l1 and l2.

val fold_right : 
  ('a -> 'b -> ('a, 'c) Stdlib.result) ->
  'a ->
  'b list ->
  ('a, 'c) Stdlib.result

fold_right f acc l folds the list l from the right with the function f, threading an accumulator of type result.

parameter f
the function to fold with.

parameter acc
the initial accumulator.

parameter l
the list to fold over.

returns
the result of folding over the list l.

val fold_right2 : 
  ('a -> 'b -> 'c -> ('a, 'd) Stdlib.result) ->
  'a ->
  'b list ->
  'c list ->
  ('a, 'd) Stdlib.result

fold_right2 f acc l1 l2 folds the lists l1 and l2 from the right with the function f, threading an accumulator of type result.

parameter f
the function to fold with.

parameter acc
the initial accumulator.

parameter l1
the first list to fold over.

parameter l2
the second list to fold over.

returns
the result of folding over the lists l1 and l2.

val map : 
  ('a -> ('b, 'c) Stdlib.result) ->
  'a list ->
  ('b list, 'c) Stdlib.result

map f l maps the function f over the list l, returning a result of type result.

parameter f
the function to map over the list.

parameter l
the list to map the function over.

returns
the result of mapping the function over the list.

val filter_map : ('a -> 'b option) -> 'a list -> ('b list, 'c) Stdlib.result

filter_map f l maps the function f over the list l, filtering out None values, and returning a result of type result.

parameter f
the function to map and filter over the list.

parameter l
the list to map the function over.

returns
the result of mapping the function over the list.

val iter : 
  ('a -> (unit, 'b) Stdlib.result) ->
  'a list ->
  (unit, 'b) Stdlib.result

iter f l applies the function f to each element of the list l, returning a result of type result wrapping unit value.

parameter f
the function to apply to each element of the list.

parameter l
the list to apply the function to.

returns
the result of applying the function to each element of the list.

val partition : 
  ('a -> bool) ->
  'a list ->
  ('a list * 'a list, 'b) Stdlib.result

partition f l partitions the list l into two lists based on the predicate f, returning a result of type result.

parameter f
the predicate to partition the list with.

parameter l
the list to partition.

returns
the result of partitioning the list.

val partition_map : 
  ('a -> ('b, 'c) Stdlib.Either.t) ->
  'a list ->
  ('b list * 'c list, 'd) Stdlib.result

partition_map f l partitions the list l into two lists based on the function f which returns an Either type, returning a result of type result.

parameter f
the function to partition the list with.

parameter l
the list to partition.

returns
the result of partitioning the list.

val for_all : 
  ('a -> (bool, 'b) Stdlib.result) ->
  'a list ->
  (bool, 'b) Stdlib.result

for_all f l checks if all elements of the list l satisfy the predicate f, returning a result of type result.

parameter f
the predicate to check each element of the list.

parameter l
the list to check.

returns
the result of checking if all elements satisfy the predicate.