Selective.Operationmodule Core : Preface_specs.Selective.COREtype 'a t = 'a Core.tThe type held by the Selective.
Mapping over from 'a and 'b and 'c to 'd over 'a t and 'b t and 'c t to 'd t.
Create a new 'a t, replacing all values in the 'b t by given a value of 'a.