DeepSeq.lhs [was: Re: [Haskell] Force evaluation]

[Dean Herington]

Here's the latest version of my DeepSeq module.

Dean


DeepSeq.lhs  --  deep strict evaluation support

The `DeepSeq` class provides a method `deepSeq` that is similar to
`seq` except that it forces deep evaluation of its first argument
before returning its second argument.

Instances of `DeepSeq` are provided for Prelude types.  Other
instances must be supplied by users of this module.

$Id: DeepSeq.lhs,v 1.5 2002/04/01 20:58:24 heringto Exp $

>  module  DeepSeq  where

>  class  DeepSeq a  where  deepSeq :: a -> b -> b

>  infixr 0 `deepSeq`, $!!

>  ($!!) :: (DeepSeq a) => (a -> b) -> a -> b
>  f $!! x = x `deepSeq` f x


>  instance  DeepSeq ()  where  deepSeq = seq

>  instance  DeepSeq Bool  where  deepSeq = seq
>  instance  DeepSeq Char  where  deepSeq = seq

>  instance  (DeepSeq a) => DeepSeq (Maybe a)  where
>    deepSeq Nothing  y = y
>    deepSeq (Just x) y = deepSeq x y

>  instance  (DeepSeq a, DeepSeq b) => DeepSeq (Either a b)  where
>    deepSeq (Left  a) y = deepSeq a y
>    deepSeq (Right b) y = deepSeq b y

>  instance  DeepSeq Ordering  where  deepSeq = seq

>  instance  DeepSeq Int       where  deepSeq = seq
>  instance  DeepSeq Integer   where  deepSeq = seq
>  instance  DeepSeq Float     where  deepSeq = seq
>  instance  DeepSeq Double    where  deepSeq = seq

>  instance  DeepSeq (a -> b)  where  deepSeq = seq

>  instance  DeepSeq (IO a)  where  deepSeq = seq

>  instance  (DeepSeq a) => DeepSeq [a]  where
>    deepSeq []     y = y
>    deepSeq (x:xs) y = deepSeq x $ deepSeq xs y

>  instance  (DeepSeq a,DeepSeq b) => DeepSeq (a,b)  where
>    deepSeq (a,b)           y = deepSeq a $ deepSeq b y
>  instance  (DeepSeq a,DeepSeq b,DeepSeq c) => DeepSeq (a,b,c)  where
>    deepSeq (a,b,c)         y = deepSeq a $ deepSeq b $ deepSeq c y
>  instance  (DeepSeq a,DeepSeq b,DeepSeq c,DeepSeq d) => DeepSeq 
>(a,b,c,d)  where
>    deepSeq (a,b,c,d)       y = deepSeq a $ deepSeq b $ deepSeq c $ deepSeq d y
>  instance  (DeepSeq a,DeepSeq b,DeepSeq c,DeepSeq d,DeepSeq e) => 
>DeepSeq (a,b,c,d,e)  where
>    deepSeq (a,b,c,d,e)     y = deepSeq a $ deepSeq b $ deepSeq c $ 
>deepSeq d $ deepSeq e y
>  instance  (DeepSeq a,DeepSeq b,DeepSeq c,DeepSeq d,DeepSeq 
>e,DeepSeq f) => DeepSeq (a,b,c,d,e,f)  where
>    deepSeq (a,b,c,d,e,f)   y = deepSeq a $ deepSeq b $ deepSeq c $ 
>deepSeq d $ deepSeq e $ deepSeq f y
>  instance  (DeepSeq a,DeepSeq b,DeepSeq c,DeepSeq d,DeepSeq 
>e,DeepSeq f,DeepSeq g) => DeepSeq (a,b,c,d,e,f,g)  where
>    deepSeq (a,b,c,d,e,f,g) y = deepSeq a $ deepSeq b $ deepSeq c $ 
>deepSeq d $ deepSeq e $ deepSeq f $ deepSeq g y