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

SYNOPSIS

Applies a finite partial function, with a backup function for undefined points.

DESCRIPTION

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, g a conventional function and x an argument, tryapply f g x tries to apply f to x as with apply f x, but instead returns g x is f is undefined on x.

FAILURE CONDITIONS

Can only fail if the backup function fails.

EXAMPLE

  # applyd undefined (fun x -> x) 1;;
  val it : int = 1
  # applyd (1 |=> 2) (fun x -> x) 1;;
  val it : int = 2