Hi,
Out of curiosity, I've been developing a tool called Dr Haskell, for a
sample run:
--------------------------------
module Test where
substitute1 :: Eq a => a -> [a] -> [a] -> [a]
substitute1 e l1 l2= [c | c <- check_elem l1]
where check_elem [] = l1
check_elem (x:xs) = if x == e then (l2 ++ xs) else [x] ++ check_elem xs
substitute2 e l l'
= concat (map subst_elem l)
where subst_elem x
| x == e = l'
| otherwise = [x]
subst3 e l [] = []
subst3 e l (x:xs) = if x == e then l ++ xs else x : subst3 e l xs
subst4 e l' = concat.map (\x->if x==e then l' else [x])
----------------------------
drhaskell Test.hs
I can apply Hints.concat_map in Test.subst4
I can apply Hints.concat_map in Test.substitute2
I can apply Hints.box_append in Test.Test.Prelude.200.check_elem
For the curious, see the darcs repo:
http://www.cs.york.ac.uk/fp/darcs/drhaskell/
(Requires Yhc)
Thanks
Neil
PS. dons also contributed some of the earlier discussion to this tool,
so deserves some credit.
On 9/18/06, wld <[EMAIL PROTECTED]> wrote:
Hi,
On 9/18/06, Joachim Breitner <[EMAIL PROTECTED]> wrote:
> Hi,
>
> Am Montag, den 18.09.2006, 16:00 +0100 schrieb Neil Mitchell:
> > > subst e l' = concat.map (\x->if x==e then l' else [x])
> > subst e l' = concatMap (\x->if x==e then l' else [x])
> > Let's save an extra character :)
> We are talking keystrokes here, so count the shift key!
>
> Greetings,
> Joachim
Sorry, couldn't resist... If we *really* talking keystrokes, it much
depends on auto-completion features of your editor! :)
V.Rudenko
--
λ is the ultimate
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