[Haskell-beginners] Usage of $

[Rein Henrichs]

The point is that there is no parsing happening here. Just evaluation.

On Mon, Jun 8, 2015 at 3:20 AM Mike Meyer <mwm at mired.org> wrote:

>
> On Jun 8, 2015 05:01, "Martin Vlk" <martin at vlkk.cz> wrote:
> >
> > Mike Meyer:
> > > s mp $ n - 1 parses as s mp (n - 1)
> > > s mp n - 1 parses as (s mp n) - 1
> >
> >
> > Hi, I think it is misleading to say that $ "parses" to something.
>
> Which is why I didn't say such a thing. The two sentences show how the
> expressions he was having trouble with are parsed.
>
> > ($) is an infix operator with type:
> >
> > ($) :: (a -> b) -> a -> b       -- Defined in ‘GHC.Base’
> > infixr 0 $
> >
> > So what it does is it takes a function on the left hand side and applies
> > it to the second argument on the right hand side. The trick is it has
> > the lowest possible precedence value (0) so everything on the right hand
> > side will be evaluated before applying the function on the left.
>
> Which explains why the expression containing a $ parses as it does, which
> is also useful information.
> _______________________________________________
> Beginners mailing list
> Beginners at haskell.org
> http://mail.haskell.org/cgi-bin/mailman/listinfo/beginners
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.haskell.org/pipermail/beginners/attachments/20150608/835fc238/attachment.html>