On Tue, Mar 24, 2009 at 2:42 PM, Manlio Perillo
Tim Newsham ha scritto:
These friends are very interested in Haskell, but it seems that the main reason why they don't start to seriously learning it, is that when they start reading some code, they feel the "Perl syndrome".
That is, code written to be "too smart", and that end up being totally illegible by Haskell novice.
I too have this feeling, from time to time.
Since someone is starting to write the Haskell coding style, I really suggest him to take this "problem" into strong consideration.
When you think about it, what you are saying is that Haskell programmers shouldn't take advantage of the extra tools that Haskell provides.
No, I'm not saying this.
But, as an example, when you read a function like:
buildPartitions xs ns = zipWith take ns . init $ scanl (flip drop) xs ns
that can be rewritten (argument reversed) as:
takeList :: [Int] -> [a] -> [[a]] takeList [] _ = [] takeList _ [] = [] takeList (n : ns) xs = head : takeList ns tail where (head, tail) = splitAt n xs ...
[...]
Manlio
Correct me if I'm wrong, but isn't this an example against your thesis? Your two definitions apparently define different things. {-# LANGUAGE NoMonomorphismRestriction #-} import Test.QuickCheck test = (\x y -> buildPartitions x y == takeList y x) buildPartitions :: [a] -> [Int] -> [[a]] buildPartitions xs ns = zipWith take ns . init $ scanl (flip drop) xs ns takeList :: [Int] -> [a] -> [[a]] takeList [] _ = [] takeList _ [] = [] takeList (n : ns) xs = head : takeList ns tail where (head, tail) = splitAt n xs {- *Main Control.Monad Data.Char Data.List> quickCheck test quickCheck test^J <interactive>:1:11: Warning: Defaulting the following constraint(s) to type `()' `Eq a' arising from a use of `test' at <interactive>:1:11-14 `Arbitrary a' arising from a use of `quickCheck' at <interactive>:1:0-14 `Show a' arising from a use of `quickCheck' at <interactive>:1:0-14 In the first argument of `quickCheck', namely `test' In a stmt of a 'do' expression: it <- quickCheck test *** Failed! Falsifiable (after 2 tests): [] [0] -} -- gwern