unless -package:either-unwrap

The reverse of when.
Generalization of unless
When the given predicate is false for the input signal.
  • Depends: now.
  • Inhibits: unless the predicate is false.
Generalization of unless.
Show a custom type error if p is false (or stuck).
if condition met, fail without a message; better avoided, since AI can't value it well
Monadic version of unless, taking the condition in the monad
Like unless, but where the test can be monadic.
A synonym of whenRight.
A synonym of whenLeft.
Do nothing on `--expert`, otherwise run the given action.
Monadic version of unless. Reverse of whenM. Conditionally don't execute the provided action.
>>> unlessM (pure False) $ putTextLn "No text :("
No text :(

>>> unlessM (pure True) $ putTextLn "Yes text :)"
Run the second value if the first value returns False
A monadic-conditional version of the unless guard.
Only perform the action if the predicate returns False. Since 0.9.2
Display something only if the condition is False (empty string otherwise).
Monadic version of unless.
>>> unlessM (pure False) $ putTextLn "No text :("
No text :(

>>> unlessM (pure True) $ putTextLn "Yes text :)"
A variant of unless with a monadic predicate.