{-# LANGUAGE Trustworthy #-} {-# LANGUAGE NoImplicitPrelude #-} ----------------------------------------------------------------------------- -- | -- Module : Data.Bool -- Copyright : (c) The University of Glasgow 2001 -- License : BSD-style (see the file libraries/base/LICENSE) -- -- Maintainer : libraries@haskell.org -- Stability : stable -- Portability : portable -- -- The 'Bool' type and related functions. -- ----------------------------------------------------------------------------- module Data.Bool ( -- * Booleans Bool(..), -- ** Operations (&&), (||), not, otherwise, bool, ) where import GHC.Base -- $setup -- >>> import Prelude -- | Case analysis for the 'Bool' type. @'bool' x y p@ evaluates to @x@ -- when @p@ is 'False', and evaluates to @y@ when @p@ is 'True'. -- -- This is equivalent to @if p then y else x@; that is, one can -- think of it as an if-then-else construct with its arguments -- reordered. -- -- @since 4.7.0.0 -- -- ==== __Examples__ -- -- Basic usage: -- -- >>> bool "foo" "bar" True -- "bar" -- >>> bool "foo" "bar" False -- "foo" -- -- Confirm that @'bool' x y p@ and @if p then y else x@ are -- equivalent: -- -- >>> let p = True; x = "bar"; y = "foo" -- >>> bool x y p == if p then y else x -- True -- >>> let p = False -- >>> bool x y p == if p then y else x -- True -- bool :: a -> a -> Bool -> a bool f _ False = f bool _ t True = t