unless is:exact

unless :: Applicative f => Bool -> f () -> f ()

base Control.Monad, relude Relude.Bool.Reexport, ghc-internal GHC.Internal.Control.Monad, verset Verset

The reverse of when.

Examples

>>> do x <- getLine
unless (x == "hi") (putStrLn "hi!")
comingupwithexamplesisdifficult
hi!

>>> unless (pi > exp 1) Nothing
Just ()

unless :: Applicative f => Bool -> f () -> f ()

base-compat Control.Monad.Compat, protolude Protolude.Monad, rio RIO.Prelude, base-prelude BasePrelude, turtle Turtle, shelly Shelly Shelly.Lifted Shelly.Pipe, classy-prelude ClassyPrelude, Cabal-syntax Distribution.Compat.Prelude, universum Universum.Bool.Reexport, ihaskell IHaskellPrelude, basement Basement.Compat.Base Basement.Imports, base-compat-batteries Control.Monad.Compat, Agda Agda.Utils.Monad, rebase Rebase.Prelude, persistent-test Init, massiv-test Test.Massiv.Utils, incipit-base Incipit.Base, LambdaHack Game.LambdaHack.Core.Prelude, cabal-install-solver Distribution.Solver.Compat.Prelude, faktory Faktory.Prelude, can-i-haz Control.Monad.Except.CoHas Control.Monad.Reader.Has, vcr Imports, yesod-paginator Yesod.Paginator.Prelude, control-monad-free Control.Monad.Free, distribution-opensuse OpenSuse.Prelude, termonad Termonad.Prelude

The reverse of when.

unless :: (Boolean bool, ToBool bool, Monad m) => bool -> m () -> m ()

cond Control.Conditional

Generalization of unless

unless :: (Monoid e) => (a -> Bool) -> Wire s e m a a

netwire Control.Wire.Interval

When the given predicate is false for the input signal.

Depends: now.
Inhibits: unless the predicate is false.

unless :: (Monad m k, PreArrow k, u ~ UnitObject k, ObjectPair k (m u) u) => Bool -> m u `k` m u

constrained-categories Control.Category.Constrained.Prelude Control.Monad.Constrained

unless :: Monoid m => Bool -> m -> m

BNFC BNFC.Utils

Generalization of unless.

unless :: () => Bool -> Cont r () -> Cont r ()

control-dsl Control.Dsl Control.Dsl.Cont