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Trying to learn Haskell. I am trying to write a simple function to remove a number from a list without using built-in function (delete...I think). For the sake of simplicity, let's assume that the input parameter is an Integer and the list is an Integer list. Here is the code I have, Please tell me…
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I'm trying to use Haskells Data.Heap module, but I'm incapable of even using it with integers. The only heap I've been capable of using is "empty", which does not take any arguments.
Later on I'll figure out how to instance for my needs, but for now I'd be glad if I was even able to test it with…
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There has been some intermingling of Scala and Haskell communities, and I have noticed now and then people commenting on stuff that's supposed to be easy in Haskell and hard and Scala. Less often (maybe because I read Scala questions, not Haskell ones), I see someone mentioning that something in Scala…
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I have problems installing ghc-mod on my linux machine. cabal worries about "happy" not being available in versione = 1.17:
$ cabal install ghc-mod
Resolving dependencies...
[1 of 1] Compiling Main ( /tmp/haskell-src-exts-1.14.0-1357/haskell-src-exts-1.14.0/Setup.hs, /tmp/haskell-src-exts-1…
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fibs :: [Int]
fibs = 0 : 1 : [ a + b | (a, b) <- zip fibs (tail fibs)]
This generates the Fibonacci sequence.
I understand the behaviour of the guards, of :, zip and tail, but I don't understand <-. What is it doing here?
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I'm trying to define any simple function that spans multiple lines in ghci, take the following as an example:
let abs n | n >= 0 = n
| otherwise = -n
So far I've tried pressing Enter after the first line:
Prelude> let abs n | n >= 0 = n
Prelude> | otherwise = -n
<interactive>:1:0:…
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I'm trying to compile this function from Learn You a Haskell for Great Good.
removeNonUppercase st = [ c | c <- st, c `elem` ['A'..'Z']]
by placing it into a removeNonUpperCase.hs file.
It compiles fine, but when passing the argument:
ghci> removeNonUppercase "Hahaha! Ahahaha!"
the…
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Intro:
While checking out snoyman's "persistent" library I found myself wanting ghci's (or another tool) assistance in figuring out stuff.
ghci's :info doesn't seem to work as nicely with type-families and data-families as it does with "plain" types:
> :info Maybe
data Maybe a = Nothing | Just…
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I am using GHC 6.12.1, in Ubuntu 10.04
When I try to use the FFI syntax for static storage, only modules running in interpreted mode (ie GHCI) work properly. Compiled modules have invalid pointers, and do not work. I'd like to know whether anybody can reproduce the problem, whether this an error…
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Why can't Haskell resolve the kind of [[]] (A list of lists)?
Why isn't it simply * - *, as I can give it a type like Int, and get [[Int]], which is of kind *.
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