You can search for identifiers within the package.
in-package search v0.2.0
val map_file : Unix.file_descr -> ?pos:int64 -> ('a, 'b) Stdlib.Bigarray.kind -> 'c Stdlib.Bigarray.layout -> bool -> int array -> ('a, 'b, 'c) Stdlib.Bigarray.Genarray.t
map_file is the same as Unix.map_file in OCaml >= 4.06.0
map_file
Unix.map_file