Personal tools

How to read Haskell

From HaskellWiki

Revision as of 10:53, 3 August 2006 by EricKow (Talk | contribs)

Jump to: navigation, search

This stub is intended to become a tutorial on reading Haskell. It's aimed at the non-Haskeller who probably doesn't care too much about trying to write code, but wants to understand it.

Contents

1 The tutorial

...needs to be written

-- insert here some horrible (for the non-Haskeller) long example
-- something we can work through slowly (and show why we find it beautiful)

1.1 Hint: order doesn't matter

Outside of a monad, it really doesn't matter what order things in Haskell code appear. So if you see something like this...

foo = whatTheHeckIsBar

you should take into account that whatTheHeckIsBar may be defined somewhere below foo

  • scope in a nutshell
  • except for monads? explain

1.2 Hint: use type signatures

When you see stuff like this

-- example please!
foo :: Bar Ping Pong -> Baz Zed Dubya -> IO (DoublePlus Good)

...don't fight it! These are type signatures and they are an incredibly useful way of getting a rough idea what a function is supposed to do.

elaborate

2 What confuses non-Haskellers

Since this tutorial is not yet written, we encourage you to note here the things which confuse non-Haskellers about the code code.

  • layout instead of semicolons?
  • super-super-concise stuff (things using liftM and liftM2)
  • the difference between
    x <- foo
    and
    x = foo