Tests if a finite partial function is defined nowhere.
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. The predicate is_undefined tests if the argument is the completely
undefined function.
FAILURE CONDITIONS
Never fails.
EXAMPLE
# let x = undefined and y = (1 |=> 2);;
val x : ('a, 'b) func =
val y : (int, int) func =
# is_undefined x;;
val it : bool = true
# is_undefined y;;
val it : bool = false