[Haskell-beginners] Top beginner mistakes
daniel.is.fischer at web.de
Thu Mar 5 13:47:35 EST 2009
Am Donnerstag, 5. März 2009 19:13 schrieb Francesco Bochicchio:
> 2009/3/4 7stud <bbxx789_05ss at yahoo.com>
> > Here are my top three:
> > ...
> > 3) Not putting parentheses around arguments of the form x:xs
> > dosomething x:xs = head xs
> I have a variation here:
> function  = ...
> function [x:xs] = ...
> Another of mine is the classical:
> print function arguments -- or variations
> but I finally learned to use '$' here .
> > In all three cases, the error messages don't help spot the problem.
At least they give a source position, so you know where to look.
But yes, "parse error" is not very specific.
> > I think that part of the problem is that haskell syntax is powerful but
> terse, and therefore is not easy for a compiler to guess the intentions in
> the programmers.
> For instance, in any other language the expression 'map f' would give the
> error "missing second parameter", while in haskell could be a partial
> function application.
> However, some of ghc messages could probably be made more
Create a ticket if you encounter a particularly unhelpful error message.
If you can suggest a better message, all the better.
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