Haskell questions

Hi, I recently decided to give Haskell another whirl, so this will become my ``Newbie Question'' thread.

First, what does anon use for Haskell dev? GHC or Hugs? Also, are there any tutorials for setting Emacs up with Haskell (GHC or Hugs) under Windows? I can't figure this out...

Next, I'm wondering why the following code doesn't work in Hugs, yet works fine in the GHC REPL:

Hugs> map toUpper "Hello World"
ERROR - Undefined variable "toUpper"
Hugs> map Char.toUpper "Hello World"
ERROR - Undefined qualified variable "Char.toUpper"
In `Yet Another Haskell Tutorial,' it says Hugs doesn't like fully qualified names, yet as you can see it fails on both qualified and unqualified. The latter input works in GHC, btw.

Thanks anon, I'll probably ask more questions if need be...

You need to load the Char module, using :load Char

First, what does anon use for Haskell dev? GHC or Hugs?

GHC.

Also, are there any tutorials for setting Emacs up with Haskell (GHC or Hugs) under Windows?

I don't know or care about Windows, but my haskell-mode setup on Emacs 22.1 is


(add-to-list 'load-path (expand-file-name "~/.emacs.d/site-lisp/haskell-mode"))
(add-to-list 'auto-mode-alist '("\\.[Hh][Ss]\\'" . haskell-mode))

(require 'haskell-mode)
(require 'inf-haskell)

(add-hook 'haskell-mode-hook 'turn-on-haskell-decl-scan)
(add-hook 'haskell-mode-hook 'turn-on-haskell-doc-mode)
(add-hook 'haskell-mode-hook 'turn-on-haskell-indent)

Also, I've set haskell-ghci-program-args to '("-fglasgow-exts" "-W").

>>2
Thanks, that seems to work.

>>3
Eh, Emacs is too hard to understand, I'll probably stick to Notepad++, but thanks anyway

Emacs is made of shit and fail.

>>5
i agree with this statement, emacs is fail and shit of made

>>4
Have you tried EclipseFP? (Haskell on Eclipse)

http://eclipsefp.sourceforge.net/

Have you tried a text editor?

OP here

>>7
Thanks, I wasn't aware there was an Eclipse plugin for Haskell. I'm using this now :)

Anyway, I'm doing the exercise in Yet Another Haskell Tute on pg 36, and I'm a bit stuck.

Given a list of integers, I need to print out each members factorial. Seems simple enough (pretend getNumList returns a list of numbers, full code removed)

module Main where

import System

fact 1 = 1
fact n = n * fact (n - 1)
printFact n = do
    putStrLn ((show n) ++ " factorial is " ++ (show (fact n)))

main = do
    numList <- getNumList
    map printFact numList   
    System.system "pause"
    return 0
I would think that the map function applies a function onto each member of a list, however I get an error `` Couldn't match expected type `IO' against inferred type `[]' ''
Uhm, okay. So I try:

let a = map printFact numList
which eliminates the error, yet produces no output. What's wrong here?

>>9
GO TO A FUCKING HASKELL BOOK SHOP NIGGAR

>>9
OP Here. Nevermind, I wrote a recursive function to do this using head and tail.

>>9
The type of map printFact numList is [IO ()], but you need to have a type of IO [()]. You can use sequence $ map printFact numList or use mapM printFact numList.

>>11
Ah, I just realized YAHT has a solutions section at the end, :P

>>10
Ok, I'm at the bookstore.
What do you recommend?

>>14
SICP

>>14
http://www.haskell.org/haskellwiki/Books
FAGGET.

>>16
>>14 is not the OP. Proceed with caution

>>14
SICP
How to Design Programs
Practical Common Lisp

Haskell School of Expression is actually pretty good. Not SICP good, but good nonetheless.

>>19
Expression you say? you must be talking about lisp!

>>20
How do I failed troll — Lesson 1
Fix'd.

[a]a[/a]
b
[c]c[/c]
[d]d[/d]
[e]e[/e]
[f]f[/f]
[g]g[/g]
[h]h[/h]
i
[j]j[/j]
[k]k[/k]
[l]l[/l]
m
[n]n[/n]
o
[p]p[/p]
[q]q[/q]
[r]r[/r]
s
[t]t[/t]
u
[v]v[/v]
[w]w[/w]
[x]x[/x]
[y]y[/y]
[z]z[/z]

[mark red]mark[/mark]
^sup

IHBT

27 Name: Anonymous 2011-09-14 1:49

http://wktk.vip2ch.com/vipper16834.jpg

"magical (star) haskell"