Module Compat.List

val is_empty : 'a list -> bool

is_empty l is true if and only if l has no elements. It is equivalent to compare_length_with l 0 = 0.

  • since OCaml 5.1
val equal : ('a -> 'a -> bool) -> 'a list -> 'a list -> bool

equal eq [a1; ...; an] [b1; ..; bm] holds when the two input lists have the same length, and for each pair of elements ai, bi at the same position we have eq ai bi.

Note: the eq function may be called even if the lists have different length. If you know your equality function is costly, you may want to check compare_lengths first.

  • since OCaml 4.12
val compare : ('a -> 'a -> int) -> 'a list -> 'a list -> int

compare cmp [a1; ...; an] [b1; ...; bm] performs a lexicographic comparison of the two input lists, using the same 'a -> 'a -> int interface as Stdlib.compare:

  • a1 :: l1 is smaller than a2 :: l2 (negative result) if a1 is smaller than a2, or if they are equal (0 result) and l1 is smaller than l2
  • the empty list [] is strictly smaller than non-empty lists

Note: the cmp function will be called even if the lists have different lengths.

  • since OCaml 4.12
val find_map : ('a -> 'b option) -> 'a list -> 'b option

find_map f l applies f to the elements of l in order, and returns the first result of the form Some v, or None if none exist.

  • since OCaml 4.10
val fold_left_map : ('acc -> 'a -> 'acc * 'b) -> 'acc -> 'a list -> 'acc * 'b list

fold_left_map is a combination of fold_left and map that threads an accumulator through calls to f.

  • since OCaml 4.11