Const.With_errorsSourceWith_errors specialises On_applicative to the error applicative.
All applicative operators are available through lowering the monad to an applicative functor.
include Traversable_types.Generic_on_applicative
with module M := Monad_exts.App(Base.Or_error)
with type ('a, 'phantom) t := t
with type 'a elt := Elt.tinclude Traversable_types.Basic_generic_on_applicative
with module M := Monad_exts.App(Base.Or_error)
with type ('a, 'phantom) t := t
with type 'a elt := Elt.tGeneric refers to the container type as 'a t, and the element type as 'a elt; substitute t/elt (arity-0) or 'a t/'a (arity-1) accordingly below.
include Generic_types.Generic
with type ('a, 'phantom) t := t
with type 'a elt := Elt.tval map_m :
t ->
f:(Elt.t -> Elt.t Monad_exts.App(Base.Or_error).t) ->
t Monad_exts.App(Base.Or_error).tmap_m c ~f maps f over every t in c, threading through an applicative functor.
Example:
(* Travesty_base_exts.List adds applicative traversals to a list;
With_errors (in S1_container) implements them on the On_error
applicative functor. *)
let f x =
Or_error.(if 0 < x then error_string "negative!" else ok x)
in
List.With_errors.map_m integers ~fval fold_map_m :
t ->
f:('acc -> Elt.t -> ('acc * Elt.t) Base.Or_error.t) ->
init:'acc ->
('acc * t) Base.Or_error.tfold_map_m c ~f ~init folds f applicatively over every t in c, threading through an accumulator with initial value init.
val fold_m :
t ->
init:'acc ->
f:('acc -> Elt.t -> 'acc Base.Or_error.t) ->
'acc Base.Or_error.tfold_m x ~init ~f folds the applicative computation f over x, starting with initial value init, and returning the final value inside the applicative effect.
iter_m x ~f iterates the computation f over x, returning the final applicative effect.
mapi_m ~f x behaves as map_m, but also supplies f with the index of the element. This index should match the actual position of the element in the container x.