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Article #717

[Haskell] head xs a x:xs

#717
From: Zbyszek Malec
Date: Wed, 07 Sep 2005 21:47
26 lines
1483 bytes
Hej
Mam w haskellu taką prostą funkjcę:

ta się kompiluje
delete :: Char -> String -> String
delete c [] = []
delete c xs | c == (head xs) = delete c (tail xs)
            | otherwise = (head xs):delete c xs


a ta już nie
delete :: Char -> String -> String
delete c [] = []
delete c x:xs | c == x = delete c xs             --linia 131
              | otherwise = x:delete c xs

Różnią sie tylko zastąpieniem  x przez wywołanie funkcji head oraz xs
poprzez tail. Dlaczego tak jest? Nie jestem biegły w Haskellu, więc może to
jest kwestia doczytania czegoś, ale nie wiem nawet dlaczego miało by to być
źle.

Błąd jaki dostaję to:
Main.hs:131:0: Parse error in pattern

-- 
Zbigniew Malec        Ustronie 104        gg:2756100
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From: Zbyszek Malec <zbyszekto@tlen.pl>
Newsgroups: pl.comp.lang.funkcyjne
Subject: [Haskell]  head xs   a    x:xs
Date: Wed, 7 Sep 2005 23:47:58 +0200
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