BasePrelude

This module reexports most of the definitions from the "base" package, which are meant to be imported unqualified.

For details check out the source.

Reimplementations of functions presented in versions of "base" newer than 4.6

Data.Bool

bool :: a -> a -> Bool -> a

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

Debug.Trace

traceShowId :: Show a => a -> a

Like traceShow but returns the shown value instead of a third value.

traceM :: Monad m => String -> m ()

Like trace but returning unit in an arbitrary monad. Allows for convenient use in do-notation. Note that the application of trace is not an action in the monad, as traceIO is in the IO monad.

... = do
  x <- ...
  traceM $ "x: " ++ show x
  y <- ...
  traceM $ "y: " ++ show y

traceShowM :: (Show a, Monad m) => a -> m ()

Like traceM, but uses show on the argument to convert it to a String.

... = do
  x <- ...
  traceShowM $ x
  y <- ...
  traceShowM $ x + y