[Haskell-beginners] Do I understand this well

[Lalitha Prasad K]

On Mon, Jun 27, 2011 at 10:22 PM, Roelof Wobben <rwobben at hotmail.com> wrote:

>
> Oke
>
>
>
> It worked now.
>
> A bumpy ride to begin something new with.
>
>
>
> Roelof
>
>
>
> ----------------------------------------
> > From: maydwell at gmail.com
> > Date: Mon, 27 Jun 2011 23:51:45 +0800
> > Subject: Re: [Haskell-beginners] Do I understand this well
> > To: rwobben at hotmail.com
> > CC: beginners at 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 <rwobben at hotmail.com>
> wrote:
> > >
> > >
> > >
> > > ________________________________
> > >> Date: Mon, 27 Jun 2011 16:14:28 +0100
> > >> Subject: Re: [Haskell-beginners] Do I understand this well
> > >> From: colinpauladams at gmail.com
> > >> To: rwobben at 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
> > >
> > >
> > > _______________________________________________
> > > Beginners mailing list
> > > Beginners at haskell.org
> > > http://www.haskell.org/mailman/listinfo/beginners
> > >
> _______________________________________________
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>

In GHCI it should be

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

Lalitha Prasad
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