It's just annoying that turning a partial function into a total one looses so much strictness, since it prevents strictness propagation. Of course, this is easily solved using a `strict' Maybe: data Perhaps a = Just' !a | Nothing'
Are other people experiencing the same thing, or is it just an academic issue and can Haskell compilers optimize it?
I am using StrictMaybe.Maybe'. I haven't tried to quantify the effect of the optimization pragmas... Wolfram ================================================================== %include polycode.fmt \section{Strict Maybe Variant} \begin{code} module Data.Rel.Utils.StrictMaybe where import Control.Monad \end{code} \begin{code} data Maybe' a = Nothing' | Just' {fromJust' :: {-# UNPACK #-} ! a} deriving (Eq, Ord, Show, Read) \end{code} \begin{code} maybe' r f Nothing' = r maybe' r f (Just' x) = f x \end{code} \begin{code} instance Functor Maybe' where fmap f Nothing' = Nothing' fmap f (Just' x) = Just' (f x) {-# INLINE fmap #-} \end{code} \begin{code} instance Monad Maybe' where return = Just' Nothing' >>= f = Nothing' (Just' x) >>= f = f x {-# INLINE (>>=) #-} fail = const Nothing' \end{code} \begin{code} instance MonadPlus Maybe' where mzero = Nothing' Nothing' `mplus` m = m m@(Just' x) `mplus` _ = m \end{code}