Data.Bool

Boolean "and", lazy in the second argument

Boolean "or", lazy in the second argument

Boolean "not"

otherwise is defined as the value True. It helps to make guards more readable. eg.

 f x | x < 0     = ...
     | otherwise = ...

Case analysis for the Bool type. bool f t p evaluates to f when p is False, and evaluates to t when p is True.

This is equivalent to if p then t else f; that is, one can think of it as an if-then-else construct with its arguments reordered.

Examples

Basic usage:

>>> bool "foo" "bar" True"bar">>> bool "foo" "bar" False"foo"

Confirm that bool f t p and if p then t else f are equivalent:

>>> let p = True; f = "bar"; t = "foo">>> bool f t p == if p then t else fTrue>>> let p = False>>> bool f t p == if p then t else fTrue