論理否定

not演算子を使います。

$ ghci
GHCi, version 6.12.2: http://www.haskell.org/ghc/  :? for help
Loading package ghc-prim ... linking ... done.
Loading package integer-gmp ... linking ... done.
Loading package base ... linking ... done.
Loading package ffi-1.0 ... linking ... done.
Prelude> not False
True
Prelude> not True
False