apply : ('a, 'b) func -> 'a -> 'b

Applies a finite partial function, failing on undefined points.

This is one of a suite of operations on finite partial functions, type ('a,'b)func. These may sometimes be preferable to ordinary functions since they permit more operations such as equality comparison, extraction of domain etc. If f is a finite partial function and x an argument, apply f x tries to apply f to x and fails if it is undefined.

  # apply undefined 1;;
  Exception: Failure "apply".
  # apply (1 |=> 2) 1;;
  val it : int = 2

|->, |=>, applyd, choose, combine, defined, dom, foldl, foldr, graph, is_undefined, mapf, ran, tryapplyd, undefine, undefined.