Допис з розмови
Newbie question...
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From: maxino <max.korob...@gmail.com>
Newsgroups: comp.lang.haskell
Subject: Newbie question...
Date: Sat, 13 Jun 2009 04:36:19 -0700 (PDT)
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Hello,
I've been studying this fascinating language for a few days so I am
pretty new to all this (especially the error messages from the
interpreter!)
I wrote this simple function, which purpose is to generate a list of
proper divisors of a number:
proper_divisors :: Int -> [Int]
proper_divisors n = [d | d <- [1 .. (floor . sqrt) n], mod n d == 0]
Saved in a file, when I :load it from GHCI 6.8.2 this is what I get:
[1 of 1] Compiling Main ( pd.hs, interpreted )
pd.hs:2:37:
No instance for (RealFrac Int)
arising from a use of `floor' at pd.hs:2:37-41
Possible fix: add an instance declaration for (RealFrac Int)
In the first argument of `(.)', namely `floor'
In the expression: (floor . sqrt) n
In a list comprehension: d <- [1 .. (floor . sqrt) n]
pd.hs:2:45:
No instance for (Floating Int)
arising from a use of `sqrt' at pd.hs:2:45-48
Possible fix: add an instance declaration for (Floating Int)
In the second argument of `(.)', namely `sqrt'
In the expression: (floor . sqrt) n
In a list comprehension: d <- [1 .. (floor . sqrt) n]
Failed, modules loaded: none.
I can imagine that perhaps it has something to do with type conflict
but I can't go any further.
Would someone help?
Thanks,
max(ino)
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