Module `Make.List`Source

List

A replacement for Stdlib.List which:

replaces the exception-raising functions by exception-safe variants,
provides Lwt-, result- and Lwt-result-aware traversors.

List is intended to shadow both Stdlib.List and Lwt_list.

Basics

Checkout Lwtreslib for an introduction to the naming and semantic convention of Lwtreslib. In a nutshell:

Stdlib functions that raise exceptions are replaced by safe variants (typically returning option).
The _e suffix is for result-aware traversors ("e" stands for "error"), _s and _p are for Lwt-aware, and _es and _ep are for Lwt-result-aware.
_e, _s, and _es traversors are fail-early: they stop traversal as soon as a failure (Error or Fail) occurs; _p and _ep traversors are best-effort: they only resolve once all of the intermediate promises have, even if a failure occurs.

Double-traversal and combine

Note that double-list traversors (iter2, map2, etc., and also combine) take an additional when_different_lengths parameter. This is to control the error that is returned when the two lists passed as arguments have different lengths.

This mechanism is a replacement for Stdlib.List.iter2 (etc.) raising Invalid_argument.

Note that, as per the fail-early behaviour mentioned above, _e, _s, and _es traversors will have already processed the common-prefix before the error is returned.

Because the best-effort behaviour of _p and _ep is unsatisfying for this failure case, double parallel traversors are omitted from this library. (Specifically, it is not obvious whether nor how the when_different_lengths error should be composed with the other errors.)

To obtain a different behaviour for sequential traversors, or to process two lists in parallel, you can use combine or any of the alternatives that handles the error differently: combine_drop, combine_with_leftovers. Finally, the rev_combine is provided to allow to avoid multiple-reversing.

Special considerations

Because they traverse the list from right-to-left, the fold_right2 function and all its variants fail with when_different_lengths before any of the processing starts. Whilst this is still within the fail-early behaviour, it may be surprising enough that it requires mentioning here.

Because they may return early, for_all2 and exists2 and all their variants may return Ok _ even though the arguments have different lengths.

Trivial values

type 'a t = 'a list =

| []
| :: of 'a * 'a list

in-monad, preallocated nil

val nil : 'a list

nil is []

val nil_e : ('a list, 'trace) Pervasives.result

nil_e is Ok []

val nil_s : 'a list Lwt.t

nil_s is Lwt.return_nil

val nil_es : ('a list, 'trace) Pervasives.result Lwt.t

nil_es is Lwt.return (Ok [])

Safe wrappers

Shadowing unsafe functions to avoid all exceptions.

Safe lookups, scans, retrievals

Return option rather than raise Not_found, Failure _, or Invalid_argument _

val hd : 'a list -> 'a option

hd xs is the head (first element) of the list or None if the list is empty.

val tl : 'a list -> 'a list option

tl xs is the tail of the list (the whole list except the first element) or None if the list is empty.

val nth : 'a list -> int -> 'a option

nth xs n is the nth element of the list or None if the list has fewer than n elements.

nth xs 0 = hd xs

val nth_opt : 'a list -> int -> 'a option

nth_opt is an alias for nth provided for backwards compatibility.

val last : 'a -> 'a list -> 'a

last x xs is the last element of the list xs or x if xs is empty.

The primary intended use for last is after destructing a list: match l with | None -> … | Some x :: xs -> last x xs but it can also be used for a default value: last default_value_if_empty xs.

val last_opt : 'a list -> 'a option

last_opt xs is the last element of the list xs or None if the list xs is empty.

val find : ('a -> bool) -> 'a list -> 'a option

find predicate xs is the first element x of the list xs such that predicate x is true or None if the list xs has no such element.

val find_opt : ('a -> bool) -> 'a list -> 'a option

find_opt is an alias for find provided for backwards compatibility.

val mem : equal:('a -> 'a -> bool) -> 'a -> 'a list -> bool

mem ~equal a l is true iff there is an element e of l such that equal a e.

val assoc : equal:('a -> 'a -> bool) -> 'a -> ('a * 'b) list -> 'b option

assoc ~equal k kvs is Some v such that (k', v) is the first pair in the list such that equal k' k or None if the list contains no such pair.

val assoc_opt : equal:('a -> 'a -> bool) -> 'a -> ('a * 'b) list -> 'b option

assoc_opt is an alias for assoc provided for backwards compatibility.

val assq : 'a -> ('a * 'b) list -> 'b option

assq k kvs is the same as assoc ~equal:Stdlib.( == ) k kvs: it uses the physical equality.

val assq_opt : 'a -> ('a * 'b) list -> 'b option

assq_opt is an alias for assq provided for backwards compatibility.

val mem_assoc : equal:('a -> 'a -> bool) -> 'a -> ('a * 'b) list -> bool

mem_assoc ~equal k l is equivalent to Option.is_some @@ assoc ~equal k l.

val mem_assq : 'a -> ('a * 'b) list -> bool

mem_assq k l is mem_assoc ~equal:Stdlib.( == ) k l.

val remove_assoc : 
  equal:('a -> 'a -> bool) ->
  'a ->
  ('a * 'b) list ->
  ('a * 'b) list

remove_assoc ~equal k l is l without the first element (k', _) such that equal k k'.

val remove_assq : 'a -> ('a * 'b) list -> ('a * 'b) list

remove_assoq k l is remove_assoc ~equal:Stdlib.( == ) k l.

Initialisation

val init : 
  when_negative_length:'trace ->
  int ->
  (int -> 'a) ->
  ('a list, 'trace) Pervasives.result

init ~when_negative_length n f is Error when_negative_length if n is strictly negative and Ok (Stdlib.List.init n f) otherwise.

Basic traversal

val length : 'a list -> int

val rev : 'a list -> 'a list

val concat : 'a list list -> 'a list

val append : 'a list -> 'a list -> 'a list

val rev_append : 'a list -> 'a list -> 'a list

val flatten : 'a list list -> 'a list

Double-list traversals

These safe-wrappers take an explicit value to handle the case of lists of unequal length.

val combine : 
  when_different_lengths:'trace ->
  'a list ->
  'b list ->
  (('a * 'b) list, 'trace) Pervasives.result

combine ~when_different_lengths l1 l2 is either

Error when_different_lengths if List.length l1 <> List.length l2
a list of pairs of elements from l1 and l2

E.g., combine ~when_different_lengths [] [] = Ok []

E.g., combine ~when_different_lengths [1; 2] ['a'; 'b'] = Ok [(1,'a'); (2, 'b')]

E.g., combine ~when_different_lengths:() [1] [] = Error ()

Note: combine ~when_different_lengths l1 l2 is equivalent to try Ok (Stdlib.List.combine l1 l2) with Invalid_argument _ -> when_different_lengths

The same equivalence almost holds for the other double traversors below. The notable difference is if the functions passed as argument to the traversors raise the Invalid_argument _ exception.

val rev_combine : 
  when_different_lengths:'trace ->
  'a list ->
  'b list ->
  (('a * 'b) list, 'trace) Pervasives.result

rev_combine ~when_different_lengths xs ys is rev (combine ~when_different_lengths xs ys) but more efficient.

val split : ('a * 'b) list -> 'a list * 'b list

val iter2 : 
  when_different_lengths:'trace ->
  ('a -> 'b -> unit) ->
  'a list ->
  'b list ->
  (unit, 'trace) Pervasives.result

val map2 : 
  when_different_lengths:'trace ->
  ('a -> 'b -> 'c) ->
  'a list ->
  'b list ->
  ('c list, 'trace) Pervasives.result

val rev_map2 : 
  when_different_lengths:'trace ->
  ('a -> 'b -> 'c) ->
  'a list ->
  'b list ->
  ('c list, 'trace) Pervasives.result

val fold_left2 : 
  when_different_lengths:'trace ->
  ('a -> 'b -> 'c -> 'a) ->
  'a ->
  'b list ->
  'c list ->
  ('a, 'trace) Pervasives.result

val fold_right2 : 
  when_different_lengths:'trace ->
  ('a -> 'b -> 'c -> 'c) ->
  'a list ->
  'b list ->
  'c ->
  ('c, 'trace) Pervasives.result

This function is not tail-recursive

val fold_left_map : ('a -> 'b -> 'a * 'c) -> 'a -> 'b list -> 'a * 'c list

fold_left_map f a xs is a combination of fold_left and map that maps over all elements of xs and threads an accumulator with initial value a through calls to f.

val for_all2 : 
  when_different_lengths:'trace ->
  ('a -> 'b -> bool) ->
  'a list ->
  'b list ->
  (bool, 'trace) Pervasives.result

val exists2 : 
  when_different_lengths:'trace ->
  ('a -> 'b -> bool) ->
  'a list ->
  'b list ->
  (bool, 'trace) Pervasives.result

Monad-aware variants

The functions below are strict extensions of the standard Stdlib.List module. It is for result-, lwt- and lwt-result-aware variants. The meaning of the suffix is as described above, in Lwtreslib, and in Sigs.Seq.

Initialisation variants

Note that for asynchronous variants (_s, _es, _p, and _ep), if the length parameter is negative, then the promise is returned already fulfilled with Error when_different_lengths.

val init_e : 
  when_negative_length:'trace ->
  int ->
  (int -> ('a, 'trace) Pervasives.result) ->
  ('a list, 'trace) Pervasives.result

val init_s : 
  when_negative_length:'trace ->
  int ->
  (int -> 'a Lwt.t) ->
  ('a list, 'trace) Pervasives.result Lwt.t

val init_es : 
  when_negative_length:'trace ->
  int ->
  (int -> ('a, 'trace) Pervasives.result Lwt.t) ->
  ('a list, 'trace) Pervasives.result Lwt.t

val init_p : 
  when_negative_length:'trace ->
  int ->
  (int -> 'a Lwt.t) ->
  ('a list, 'trace) Pervasives.result Lwt.t

Query variants

val find_e : 
  ('a -> (bool, 'trace) Pervasives.result) ->
  'a list ->
  ('a option, 'trace) Pervasives.result

val find_s : ('a -> bool Lwt.t) -> 'a list -> 'a option Lwt.t

val find_es : 
  ('a -> (bool, 'trace) Pervasives.result Lwt.t) ->
  'a list ->
  ('a option, 'trace) Pervasives.result Lwt.t

val filter : ('a -> bool) -> 'a list -> 'a list

val rev_filter : ('a -> bool) -> 'a list -> 'a list

rev_filter f l is rev (filter f l) but more efficient.

val rev_filter_some : 'a option list -> 'a list

val filter_some : 'a option list -> 'a list

val rev_filter_ok : ('a, 'b) Pervasives.result list -> 'a list

val filter_ok : ('a, 'b) Pervasives.result list -> 'a list

val rev_filter_error : ('a, 'b) Pervasives.result list -> 'b list

val filter_error : ('a, 'b) Pervasives.result list -> 'b list

val rev_filter_e : 
  ('a -> (bool, 'trace) Pervasives.result) ->
  'a list ->
  ('a list, 'trace) Pervasives.result

val filter_e : 
  ('a -> (bool, 'trace) Pervasives.result) ->
  'a list ->
  ('a list, 'trace) Pervasives.result

val rev_filter_s : ('a -> bool Lwt.t) -> 'a list -> 'a list Lwt.t

val filter_s : ('a -> bool Lwt.t) -> 'a list -> 'a list Lwt.t

val rev_filter_es : 
  ('a -> (bool, 'trace) Pervasives.result Lwt.t) ->
  'a list ->
  ('a list, 'trace) Pervasives.result Lwt.t

val filter_es : 
  ('a -> (bool, 'trace) Pervasives.result Lwt.t) ->
  'a list ->
  ('a list, 'trace) Pervasives.result Lwt.t

val filter_p : ('a -> bool Lwt.t) -> 'a list -> 'a list Lwt.t

val rev_partition : ('a -> bool) -> 'a list -> 'a list * 'a list

val partition : ('a -> bool) -> 'a list -> 'a list * 'a list

val rev_partition_result : ('a, 'b) Pervasives.result list -> 'a list * 'b list

val partition_result : ('a, 'b) Pervasives.result list -> 'a list * 'b list

val rev_partition_e : 
  ('a -> (bool, 'trace) Pervasives.result) ->
  'a list ->
  ('a list * 'a list, 'trace) Pervasives.result

val partition_e : 
  ('a -> (bool, 'trace) Pervasives.result) ->
  'a list ->
  ('a list * 'a list, 'trace) Pervasives.result

val rev_partition_s : 
  ('a -> bool Lwt.t) ->
  'a list ->
  ('a list * 'a list) Lwt.t

val partition_s : ('a -> bool Lwt.t) -> 'a list -> ('a list * 'a list) Lwt.t

val rev_partition_es : 
  ('a -> (bool, 'trace) Pervasives.result Lwt.t) ->
  'a list ->
  ('a list * 'a list, 'trace) Pervasives.result Lwt.t

val partition_es : 
  ('a -> (bool, 'trace) Pervasives.result Lwt.t) ->
  'a list ->
  ('a list * 'a list, 'trace) Pervasives.result Lwt.t

val partition_p : ('a -> bool Lwt.t) -> 'a list -> ('a list * 'a list) Lwt.t

val iter : ('a -> unit) -> 'a list -> unit

Traversal variants

val iter_e : 
  ('a -> (unit, 'trace) Pervasives.result) ->
  'a list ->
  (unit, 'trace) Pervasives.result

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

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

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

val iteri : (int -> 'a -> unit) -> 'a list -> unit

val iteri_e : 
  (int -> 'a -> (unit, 'trace) Pervasives.result) ->
  'a list ->
  (unit, 'trace) Pervasives.result

val iteri_s : (int -> 'a -> unit Lwt.t) -> 'a list -> unit Lwt.t

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

val iteri_p : (int -> 'a -> unit Lwt.t) -> 'a list -> unit Lwt.t

val map : ('a -> 'b) -> 'a list -> 'b list

val map_e : 
  ('a -> ('b, 'trace) Pervasives.result) ->
  'a list ->
  ('b list, 'trace) Pervasives.result

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

val map_es : 
  ('a -> ('b, 'trace) Pervasives.result Lwt.t) ->
  'a list ->
  ('b list, 'trace) Pervasives.result Lwt.t

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

val mapi : (int -> 'a -> 'b) -> 'a list -> 'b list

val mapi_e : 
  (int -> 'a -> ('b, 'trace) Pervasives.result) ->
  'a list ->
  ('b list, 'trace) Pervasives.result

val mapi_s : (int -> 'a -> 'b Lwt.t) -> 'a list -> 'b list Lwt.t

val mapi_es : 
  (int -> 'a -> ('b, 'trace) Pervasives.result Lwt.t) ->
  'a list ->
  ('b list, 'trace) Pervasives.result Lwt.t

val mapi_p : (int -> 'a -> 'b Lwt.t) -> 'a list -> 'b list Lwt.t

val rev_map : ('a -> 'b) -> 'a list -> 'b list

val rev_mapi : (int -> 'a -> 'b) -> 'a list -> 'b list

val rev_map_e : 
  ('a -> ('b, 'trace) Pervasives.result) ->
  'a list ->
  ('b list, 'trace) Pervasives.result

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

val rev_map_es : 
  ('a -> ('b, 'trace) Pervasives.result Lwt.t) ->
  'a list ->
  ('b list, 'trace) Pervasives.result Lwt.t

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

val rev_mapi_e : 
  (int -> 'a -> ('b, 'trace) Pervasives.result) ->
  'a list ->
  ('b list, 'trace) Pervasives.result

val rev_mapi_s : (int -> 'a -> 'b Lwt.t) -> 'a list -> 'b list Lwt.t

val rev_mapi_es : 
  (int -> 'a -> ('b, 'trace) Pervasives.result Lwt.t) ->
  'a list ->
  ('b list, 'trace) Pervasives.result Lwt.t

val rev_mapi_p : (int -> 'a -> 'b Lwt.t) -> 'a list -> 'b list Lwt.t

val rev_filter_map : ('a -> 'b option) -> 'a list -> 'b list

val rev_filter_map_e : 
  ('a -> ('b option, 'trace) Pervasives.result) ->
  'a list ->
  ('b list, 'trace) Pervasives.result

val filter_map_e : 
  ('a -> ('b option, 'trace) Pervasives.result) ->
  'a list ->
  ('b list, 'trace) Pervasives.result

val rev_filter_map_s : ('a -> 'b option Lwt.t) -> 'a list -> 'b list Lwt.t

val filter_map : ('a -> 'b option) -> 'a list -> 'b list

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

val rev_filter_map_es : 
  ('a -> ('b option, 'trace) Pervasives.result Lwt.t) ->
  'a list ->
  ('b list, 'trace) Pervasives.result Lwt.t

val filter_map_es : 
  ('a -> ('b option, 'trace) Pervasives.result Lwt.t) ->
  'a list ->
  ('b list, 'trace) Pervasives.result Lwt.t

val filter_map_p : ('a -> 'b option Lwt.t) -> 'a list -> 'b list Lwt.t

val concat_map : ('a -> 'b list) -> 'a list -> 'b list

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

val concat_map_e : 
  ('a -> ('b list, 'error) Pervasives.result) ->
  'a list ->
  ('b list, 'error) Pervasives.result

val concat_map_es : 
  ('a -> ('b list, 'error) Pervasives.result Lwt.t) ->
  'a list ->
  ('b list, 'error) Pervasives.result Lwt.t

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

val fold_left : ('a -> 'b -> 'a) -> 'a -> 'b list -> 'a

val fold_left_e : 
  ('a -> 'b -> ('a, 'trace) Pervasives.result) ->
  'a ->
  'b list ->
  ('a, 'trace) Pervasives.result

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

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

val fold_left_map_e : 
  ('a -> 'b -> ('a * 'c, 'trace) Pervasives.result) ->
  'a ->
  'b list ->
  ('a * 'c list, 'trace) Pervasives.result

fold_left_map_e f a xs is a combination of fold_left_e and map_e that maps over all elements of xs and threads an accumulator with initial value a through calls to f. The list is traversed from left to right and the first encountered error is returned.

val fold_left_map_s : 
  ('a -> 'b -> ('a * 'c) Lwt.t) ->
  'a ->
  'b list ->
  ('a * 'c list) Lwt.t

fold_left_map_s f a xs is a combination of fold_left_s and map_s that maps over all elements of xs and threads an accumulator with initial value a through calls to f.

val fold_left_map_es : 
  ('a -> 'b -> ('a * 'c, 'trace) Pervasives.result Lwt.t) ->
  'a ->
  'b list ->
  ('a * 'c list, 'trace) Pervasives.result Lwt.t

fold_left_map_es f a xs is a combination of fold_left_es and map_es that maps over all elements of xs and threads an accumulator with initial value a through calls to f. The list is traversed from left to right and the first encountered error is returned.

val fold_left_i : (int -> 'a -> 'b -> 'a) -> 'a -> 'b list -> 'a

val fold_left_i_e : 
  (int -> 'a -> 'b -> ('a, 'trace) Pervasives.result) ->
  'a ->
  'b list ->
  ('a, 'trace) Pervasives.result

val fold_left_i_s : (int -> 'a -> 'b -> 'a Lwt.t) -> 'a -> 'b list -> 'a Lwt.t

val fold_left_i_es : 
  (int -> 'a -> 'b -> ('a, 'trace) Pervasives.result Lwt.t) ->
  'a ->
  'b list ->
  ('a, 'trace) Pervasives.result Lwt.t

val fold_right : ('a -> 'b -> 'b) -> 'a list -> 'b -> 'b

This function is not tail-recursive

val fold_right_e : 
  ('a -> 'b -> ('b, 'trace) Pervasives.result) ->
  'a list ->
  'b ->
  ('b, 'trace) Pervasives.result

This function is not tail-recursive

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

This function is not tail-recursive

val fold_right_es : 
  ('a -> 'b -> ('b, 'trace) Pervasives.result Lwt.t) ->
  'a list ->
  'b ->
  ('b, 'trace) Pervasives.result Lwt.t

This function is not tail-recursive

Double-traversal variants

As mentioned above, there are no _p and _ep double-traversors. Use combine (and variants) to circumvent this.

val iter2_e : 
  when_different_lengths:'trace ->
  ('a -> 'b -> (unit, 'trace) Pervasives.result) ->
  'a list ->
  'b list ->
  (unit, 'trace) Pervasives.result

val iter2_s : 
  when_different_lengths:'trace ->
  ('a -> 'b -> unit Lwt.t) ->
  'a list ->
  'b list ->
  (unit, 'trace) Pervasives.result Lwt.t

val iter2_es : 
  when_different_lengths:'trace ->
  ('a -> 'b -> (unit, 'trace) Pervasives.result Lwt.t) ->
  'a list ->
  'b list ->
  (unit, 'trace) Pervasives.result Lwt.t

val map2_e : 
  when_different_lengths:'trace ->
  ('a -> 'b -> ('c, 'trace) Pervasives.result) ->
  'a list ->
  'b list ->
  ('c list, 'trace) Pervasives.result

val map2_s : 
  when_different_lengths:'trace ->
  ('a -> 'b -> 'c Lwt.t) ->
  'a list ->
  'b list ->
  ('c list, 'trace) Pervasives.result Lwt.t

val map2_es : 
  when_different_lengths:'trace ->
  ('a -> 'b -> ('c, 'trace) Pervasives.result Lwt.t) ->
  'a list ->
  'b list ->
  ('c list, 'trace) Pervasives.result Lwt.t

val rev_map2_e : 
  when_different_lengths:'trace ->
  ('a -> 'b -> ('c, 'trace) Pervasives.result) ->
  'a list ->
  'b list ->
  ('c list, 'trace) Pervasives.result

val rev_map2_s : 
  when_different_lengths:'trace ->
  ('a -> 'b -> 'c Lwt.t) ->
  'a list ->
  'b list ->
  ('c list, 'trace) Pervasives.result Lwt.t

val rev_map2_es : 
  when_different_lengths:'trace ->
  ('a -> 'b -> ('c, 'trace) Pervasives.result Lwt.t) ->
  'a list ->
  'b list ->
  ('c list, 'trace) Pervasives.result Lwt.t

val fold_left2_e : 
  when_different_lengths:'trace ->
  ('a -> 'b -> 'c -> ('a, 'trace) Pervasives.result) ->
  'a ->
  'b list ->
  'c list ->
  ('a, 'trace) Pervasives.result

val fold_left2_s : 
  when_different_lengths:'trace ->
  ('a -> 'b -> 'c -> 'a Lwt.t) ->
  'a ->
  'b list ->
  'c list ->
  ('a, 'trace) Pervasives.result Lwt.t

val fold_left2_es : 
  when_different_lengths:'trace ->
  ('a -> 'b -> 'c -> ('a, 'trace) Pervasives.result Lwt.t) ->
  'a ->
  'b list ->
  'c list ->
  ('a, 'trace) Pervasives.result Lwt.t

val fold_right2_e : 
  when_different_lengths:'trace ->
  ('a -> 'b -> 'c -> ('c, 'trace) Pervasives.result) ->
  'a list ->
  'b list ->
  'c ->
  ('c, 'trace) Pervasives.result

This function is not tail-recursive

val fold_right2_s : 
  when_different_lengths:'trace ->
  ('a -> 'b -> 'c -> 'c Lwt.t) ->
  'a list ->
  'b list ->
  'c ->
  ('c, 'trace) Pervasives.result Lwt.t

This function is not tail-recursive

val fold_right2_es : 
  when_different_lengths:'trace ->
  ('a -> 'b -> 'c -> ('c, 'trace) Pervasives.result Lwt.t) ->
  'a list ->
  'b list ->
  'c ->
  ('c, 'trace) Pervasives.result Lwt.t

This function is not tail-recursive

Scanning variants

val for_all : ('a -> bool) -> 'a list -> bool

val for_all_e : 
  ('a -> (bool, 'trace) Pervasives.result) ->
  'a list ->
  (bool, 'trace) Pervasives.result

val for_all_s : ('a -> bool Lwt.t) -> 'a list -> bool Lwt.t

val for_all_es : 
  ('a -> (bool, 'trace) Pervasives.result Lwt.t) ->
  'a list ->
  (bool, 'trace) Pervasives.result Lwt.t

val for_all_p : ('a -> bool Lwt.t) -> 'a list -> bool Lwt.t

val exists : ('a -> bool) -> 'a list -> bool

val exists_e : 
  ('a -> (bool, 'trace) Pervasives.result) ->
  'a list ->
  (bool, 'trace) Pervasives.result

val exists_s : ('a -> bool Lwt.t) -> 'a list -> bool Lwt.t

val exists_es : 
  ('a -> (bool, 'trace) Pervasives.result Lwt.t) ->
  'a list ->
  (bool, 'trace) Pervasives.result Lwt.t

val exists_p : ('a -> bool Lwt.t) -> 'a list -> bool Lwt.t

Double-scanning variants

As mentioned above, there are no _p and _ep double-scanners. Use combine (and variants) to circumvent this.

val for_all2_e : 
  when_different_lengths:'trace ->
  ('a -> 'b -> (bool, 'trace) Pervasives.result) ->
  'a list ->
  'b list ->
  (bool, 'trace) Pervasives.result

val for_all2_s : 
  when_different_lengths:'trace ->
  ('a -> 'b -> bool Lwt.t) ->
  'a list ->
  'b list ->
  (bool, 'trace) Pervasives.result Lwt.t

val for_all2_es : 
  when_different_lengths:'trace ->
  ('a -> 'b -> (bool, 'trace) Pervasives.result Lwt.t) ->
  'a list ->
  'b list ->
  (bool, 'trace) Pervasives.result Lwt.t

val exists2_e : 
  when_different_lengths:'trace ->
  ('a -> 'b -> (bool, 'trace) Pervasives.result) ->
  'a list ->
  'b list ->
  (bool, 'trace) Pervasives.result

val exists2_s : 
  when_different_lengths:'trace ->
  ('a -> 'b -> bool Lwt.t) ->
  'a list ->
  'b list ->
  (bool, 'trace) Pervasives.result Lwt.t

val exists2_es : 
  when_different_lengths:'trace ->
  ('a -> 'b -> (bool, 'trace) Pervasives.result Lwt.t) ->
  'a list ->
  'b list ->
  (bool, 'trace) Pervasives.result Lwt.t

Combine variants

These are primarily intended to be used for preprocessing before applying a traversor to the resulting list of pairs. They give alternatives to the when_different_lengths mechanism of the immediate double-traversors above.

In case the semantic of, say, map2_es was unsatisfying, one can use map_es on a combine-preprocessed pair of lists. The different variants of combine give different approaches to different-length handling.

val combine_drop : 'a list -> 'b list -> ('a * 'b) list

combine_drop ll lr is a list l of pairs of elements taken from the common-length prefix of ll and lr. The suffix of whichever list is longer (if any) is dropped.

More formally nth l n is:

None if n >= min (length ll) (length lr)
Some (Option.get @@ nth ll n, Option.get @@ nth lr n) otherwise

type ('a, 'b) left_or_right_list = [

| `Left of 'a list
| `Right of 'b list

]

A type like result but which is symmetric

val combine_with_leftovers : 
  'a list ->
  'b list ->
  ('a * 'b) list * ('a, 'b) left_or_right_list option

combine_with_leftovers ll lr is a tuple (combined, leftover) where combined is combine_drop ll lr and leftover is either `Left lsuffix or `Right rsuffix depending on which of ll or lr is longer. leftover is None if the two lists have the same length.

compare / equal

val compare : ('a -> 'a -> int) -> 'a list -> 'a list -> int

val compare_lengths : 'a list -> 'b list -> int

val compare_length_with : 'a list -> int -> int

val equal : ('a -> 'a -> bool) -> 'a list -> 'a list -> bool

Sorting

val sort : ('a -> 'a -> int) -> 'a list -> 'a list

val stable_sort : ('a -> 'a -> int) -> 'a list -> 'a list

val fast_sort : ('a -> 'a -> int) -> 'a list -> 'a list

val sort_uniq : ('a -> 'a -> int) -> 'a list -> 'a list

conversion

val to_seq : 'a list -> 'a Seq.t

val of_seq : 'a Seq.t -> 'a list

val init_ep : 
  when_negative_length:'error ->
  int ->
  (int -> ('a, 'error Error_monad.trace) Pervasives.result Lwt.t) ->
  ('a list, 'error Error_monad.trace) Pervasives.result Lwt.t

val filter_ep : 
  ('a -> (bool, 'error Error_monad.trace) Pervasives.result Lwt.t) ->
  'a list ->
  ('a list, 'error Error_monad.trace) Pervasives.result Lwt.t

val partition_ep : 
  ('a -> (bool, 'error Error_monad.trace) Pervasives.result Lwt.t) ->
  'a list ->
  ('a list * 'a list, 'error Error_monad.trace) Pervasives.result Lwt.t

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

val iteri_ep : 
  (int -> 'a -> (unit, 'error Error_monad.trace) Pervasives.result Lwt.t) ->
  'a list ->
  (unit, 'error Error_monad.trace) Pervasives.result Lwt.t

val map_ep : 
  ('a -> ('b, 'error Error_monad.trace) Pervasives.result Lwt.t) ->
  'a list ->
  ('b list, 'error Error_monad.trace) Pervasives.result Lwt.t

val mapi_ep : 
  (int -> 'a -> ('b, 'error Error_monad.trace) Pervasives.result Lwt.t) ->
  'a list ->
  ('b list, 'error Error_monad.trace) Pervasives.result Lwt.t

val rev_map_ep : 
  ('a -> ('b, 'error Error_monad.trace) Pervasives.result Lwt.t) ->
  'a list ->
  ('b list, 'error Error_monad.trace) Pervasives.result Lwt.t

val rev_mapi_ep : 
  (int -> 'a -> ('b, 'error Error_monad.trace) Pervasives.result Lwt.t) ->
  'a list ->
  ('b list, 'error Error_monad.trace) Pervasives.result Lwt.t

val filter_map_ep : 
  ('a -> ('b option, 'error Error_monad.trace) Pervasives.result Lwt.t) ->
  'a list ->
  ('b list, 'error Error_monad.trace) Pervasives.result Lwt.t

val concat_map_ep : 
  ('a -> ('b list, 'error Error_monad.trace) Pervasives.result Lwt.t) ->
  'a list ->
  ('b list, 'error Error_monad.trace) Pervasives.result Lwt.t

val for_all_ep : 
  ('a -> (bool, 'error Error_monad.trace) Pervasives.result Lwt.t) ->
  'a list ->
  (bool, 'error Error_monad.trace) Pervasives.result Lwt.t

val exists_ep : 
  ('a -> (bool, 'error Error_monad.trace) Pervasives.result Lwt.t) ->
  'a list ->
  (bool, 'error Error_monad.trace) Pervasives.result Lwt.t

Install

dune-project
Dependency

Authors

Maintainers

Sources

doc/octez-proto-libs.protocol-environment/Tezos_protocol_environment/V4/Make/List/index.html

Module `Make.List`Source

List

Basics

Double-traversal and combine

Special considerations

Trivial values

Safe wrappers

Safe lookups, scans, retrievals

Initialisation

Basic traversal

Double-list traversals

Monad-aware variants

Initialisation variants

Query variants

Double-traversal variants

Scanning variants

Double-scanning variants

Combine variants

compare / equal

Sorting

conversion

package octez-proto-libs

Install

dune-project Dependency

Authors

Maintainers

Sources

doc/octez-proto-libs.protocol-environment/Tezos_protocol_environment/V4/Make/List/index.html

Module Make.ListSource

List

Basics

Double-traversal and combine

Special considerations

Trivial values

Safe wrappers

Safe lookups, scans, retrievals

Initialisation

Basic traversal

Double-list traversals

Monad-aware variants

Initialisation variants

Query variants

Double-traversal variants

Scanning variants

Double-scanning variants

Combine variants

compare / equal

Sorting

conversion

dune-project
Dependency

Module `Make.List`Source