[Haskell-beginners] Re: strange take result--explanation?

[Francesco Bochicchio]

2009/3/12 7stud <bbxx789_05ss at yahoo.com>

> 7stud <bbxx789_05ss <at> yahoo.com> writes:
> >
> > Why does
> >
> > take (0 - 1) [1, 2, 3]
> >
> > produce a result but not
> >
> > take -1 [1, 2, 3]
> >
> > ?  Thanks
> >
>
> Well, immediately after I hit the submit button, I thought I'd try this:
>
> *Main> take (-1) [1, 2, 3]
> []
>
> So why are the parentheses needed there?
>
>
>

I think because take -1 [1,2,3] is parsed as (take  - 1 ) [1,2,3] or
something like that.
If you look to the error message, and translate the haskellese in plain
english, it says so.

"In the second argument of `(-)', namely `1 [1, 2, 3]' " :
so it looks like is looking for the two arguments of infix operator (-), the
first being 'take'.
But I don't understand because it says that 1 [1,2,3] is a single
argument...
"In the definition of `it': it = take - 1 [1, 2, 3]"
notice the blank between the minus sign and 1: even if you write -1, it
understands - 1.

So, ghc is trying to be helpful here :-)

Ciao
-----
FB
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