Re: [Haskell-beginners] Do I understand this well

Oke It worked now. A bumpy ride to begin something new with. Roelof ----------------------------------------

From: maydwell@gmail.com Date: Mon, 27 Jun 2011 23:51:45 +0800 Subject: Re: [Haskell-beginners] Do I understand this well To: rwobben@hotmail.com CC: beginners@haskell.org

Top-level bindings are done in ghci with let:

let (x, y) = addVectors (3.0, 4.5, -3.4, -5.6)

On Mon, Jun 27, 2011 at 11:49 PM, Roelof Wobben wrote:

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Date: Mon, 27 Jun 2011 16:14:28 +0100 Subject: Re: [Haskell-beginners] Do I understand this well From: colinpauladams@gmail.com To: rwobben@hotmail.com

No.

You are onfusing defining a function with using it.

addVectors (x1, y1) (x2, y2) = (x1 + x2, y1 + y2)

defines the function addVectors

(x, y) = addVectors (3.0, 4.5, -3.4, -5.6)

calls the function, and binds x and y to the components of the result (pattern matching).

Alternatively:

fst . addVectors (3.0, 4.5, -3.4, -5.6)

will return the x-compnent of the result (by composing functions)

Oke,

I understand that I think

But when I ghci I enter :

(x, y) = addVectors (3.0, 4.5, -3.4, -5.6)

after I made a file with the file defenition.

I get this error :

:1:7 parse error on input =

So something is not right here.

Roelof

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