package tezos-lwt-result-stdlib

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package tezos-lwt-result-stdlib
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include Bare_sigs.Seq_s.S
type +'a node =
  1. | Nil
  2. | Cons of 'a * 'a t

This is similar to S.t but the suspended node is a promise.

and 'a t = unit -> 'a node Lwt.t
val empty : 'a t

empty is a sequence with no elements.

val return : 'a -> 'a t

return x is a sequence with the single element x.

val return_s : 'a Lwt.t -> 'a t

return_s p is a sequence with the value the promise p resolves to as its single element.

val cons : 'a -> 'a t -> 'a t

cons x s is the sequence containing x followed by s. It is a whole sequence if s is.

val cons_s : 'a Lwt.t -> 'a t -> 'a t

cons_s p s is the sequence containing the value the promise p resolves to, followed by s.

val append : 'a t -> 'a t -> 'a t

append s1 s2 is a sequence s containing the elements of s1 followed by the elements of s2.

val first : 'a t -> 'a option Lwt.t

first s resolves to None if s is empty (and its suspended node resolves), it resolves to Some x where x is the first element of s, it does not resolve if the promised node of s doesn't.

Note that first forces the first element of the sequence, which can have side-effects or be computationally expensive. Consider, e.g., the case where s = filter (fun …) s': first s can force multiple of the values from s'.

val fold_left : ('a -> 'b -> 'a) -> 'a -> 'b t -> 'a Lwt.t

Similar to fold_left but applies to Lwt-suspended sequences. Because the nodes are suspended in promises, traversing may yield and, consequently, the function fold_left returns a promise.

val fold_left_e : ('a -> 'b -> ('a, 'trace) result) -> 'a -> 'b t -> ('a, 'trace) result Lwt.t

Similar to fold_left but wraps the traversal in result. The traversal is interrupted if one of the step returns an Error _.

val fold_left_s : ('a -> 'b -> 'a Lwt.t) -> 'a -> 'b t -> 'a Lwt.t

Similar to fold_left but the folder is within Lwt.

val fold_left_es : ('a -> 'b -> ('a, 'trace) result Lwt.t) -> 'a -> 'b t -> ('a, 'trace) result Lwt.t

Similar to fold_left but the folder is within result-Lwt. Traversal is interrupted if one of the step resolves to an Error _.

val iter : ('a -> unit) -> 'a t -> unit Lwt.t

iter f s applies f to each element of s.

val iter_e : ('a -> (unit, 'trace) result) -> 'a t -> (unit, 'trace) result Lwt.t

Similar to iter but wraps the iteration in result. The iteration is interrupted if one of the steps returns an Error _.

val iter_s : ('a -> unit Lwt.t) -> 'a t -> unit Lwt.t

Similar to iter but wraps the iteration in Lwt. Each step of the iteration is started after the previous one is resolved.

val iter_es : ('a -> (unit, 'trace) result Lwt.t) -> 'a t -> (unit, 'trace) result Lwt.t

Similar to iter but wraps the iteration in result Lwt.t. Each step of the iteration is started after the previous one resolved. The iteration is interrupted if one of the promise is rejected of fulfilled with an Error _.

val iter_ep : ('a -> (unit, 'trace) result Lwt.t) -> 'a t -> (unit, 'trace list) result Lwt.t

Similar to iter but wraps the iteration in result Lwt.t. The steps of the iteration are started concurrently: one iteration starts as soon as a node becomes resolved. The promise iter_ep resolves once all the promises of the traversal resolve. At this point it either:

  • is rejected if at least one of the promises is, otherwise
  • is fulfilled with Error _ if at least one of the promises is, otherwise
  • is fulfilled with Ok () if all the promises are.
val iter_p : ('a -> unit Lwt.t) -> 'a t -> unit Lwt.t

Similar to iter but wraps the iteration in Lwt. The steps of the iteration are started concurrently: one iteration is started as soon as the node becomes resolved. The promise iter_p f s is resolved only once all the promises of the iteration are. At this point it is either fulfilled if all promises are, or rejected if at least one of them is.

val map : ('a -> 'b) -> 'a t -> 'b t
val map_s : ('a -> 'b Lwt.t) -> 'a t -> 'b t
val filter : ('a -> bool) -> 'a t -> 'a t
val filter_s : ('a -> bool Lwt.t) -> 'a t -> 'a t

Similar to filter but wraps the transformation in Lwt.t. Each test of the predicate is done sequentially, only starting once the previous one has resolved.

val filter_map : ('a -> 'b option) -> 'a t -> 'b t
val filter_map_s : ('a -> 'b option Lwt.t) -> 'a t -> 'b t

Similar to filter_map but within Lwt.t. Not lazy and not tail-recursive.

val unfold : ('b -> ('a * 'b) option) -> 'b -> 'a t
val unfold_s : ('b -> ('a * 'b) option Lwt.t) -> 'b -> 'a t
val of_seq : 'a Seq.t -> 'a t
val of_seq_s : 'a Lwt.t Seq.t -> 'a t
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