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[[Category:How to]]
 
[[Category:How to]]
   
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* [[Cookbook/General hints|General hints]]
 
* [[Cookbook/Strings|Strings]]
 
* [[Cookbook/Strings|Strings]]
 
* [[Cookbook/Numbers|Numbers]]
 
* [[Cookbook/Numbers|Numbers]]
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This page is based on the Scheme Cookbook at
 
This page is based on the Scheme Cookbook at
 
http://schemecookbook.org/Cookbook/WebHome'''
 
http://schemecookbook.org/Cookbook/WebHome'''
== Prelude ==
 
 
A lot of functions are defined in the "[http://www.haskell.org/hoogle/?q=Prelude Prelude]". Also, if you ever want to search for a function, based on the name, type or module, take a look at the excellent [http://www.haskell.org/hoogle/ Hoogle]. This is for a lot of people a must-have while debugging and writing Haskell programs.
 
 
== GHCi/Hugs ==
 
=== GHCi interaction ===
 
To start GHCi from a command prompt, simply type `ghci'
 
 
$ ghci
 
___ ___ _
 
/ _ \ /\ /\/ __(_)
 
/ /_\// /_/ / / | | GHC Interactive, version 6.6, for Haskell 98.
 
/ /_\\/ __ / /___| | http://www.haskell.org/ghc/
 
\____/\/ /_/\____/|_| Type :? for help.
 
 
Loading package base ... linking ... done.
 
Prelude>
 
 
[http://haskell.org/ghc/docs/latest/html/libraries/base/Prelude.html Prelude] is the "base" library of Haskell.
 
 
To create variables at the GHCi prompt, use `let'
 
<haskell>
 
Prelude> let x = 5
 
Prelude> x
 
5
 
Prelude> let y = 3
 
Prelude> y
 
3
 
Prelude> x + y
 
8
 
</haskell>
 
 
`let' is also the way to create simple functions at the GHCi prompt
 
<haskell>
 
Prelude> let fact n = product [1..n]
 
Prelude> fact 5
 
120
 
</haskell>
 
 
 
=== Checking Types ===
 
To check the type of an expression or function, use the command `:t'
 
<haskell>
 
Prelude> :t x
 
x :: Integer
 
Prelude> :t "Hello"
 
"Hello" :: [Char]
 
</haskell>
 
Haskell has the following types defined in the [http://haskell.org/ghc/docs/latest/html/libraries/base/Prelude.html Standard Prelude].
 
<haskell>
 
Int -- bounded, word-sized integers
 
Integer -- unbounded integers
 
Double -- floating point values
 
Char -- characters
 
String -- equivalent to [Char], strings are lists of characters
 
() -- the unit type
 
Bool -- booleans
 
[a] -- lists
 
(a,b) -- tuples / product types
 
Either a b -- sum types
 
Maybe a -- optional values
 
</haskell>
 

Revision as of 10:44, 23 April 2009


This article is a draft, with further revisions actively invited. Drafts are typically different than stubs in that these articles are in an active edit process. Feel free to help by expanding the article.

We need to start a Haskell centered cookbook (aka, not a PLEAC clone)

This page is based on the Scheme Cookbook at http://schemecookbook.org/Cookbook/WebHome