> -----Original Message-----
> From: Manuel M. T. Chakravarty [SMTP:[EMAIL PROTECTED]]
> Sent: Tuesday, May 22, 2001 6:55 AM
> To: [EMAIL PROTECTED]
> Cc: [EMAIL PROTECTED]
> Subject: Re: Functional programming in Python
>
> Pertti Kellomäki <[EMAIL PROTECTED]> wrote,
>
> > > From: Ketil Malde <[EMAIL PROTECTED]>
> > > "Manuel M. T. Chakravarty" <[EMAIL PROTECTED]> writes:
> > > > You want to be able to write
> > >
> > > > f 1 2 + g 3 4
> > >
> > > > instead of
> > >
> > > > (f 1 2) + (g 3 4)
> > >
> > > I do? Personally, I find it a bit confusing, and I still often get it
> > > wrong on the first attempt.
> >
> > Same here. A while back someone said something along the lines that
> people
> > come to Haskell because of the syntax. For me it is the other way
> around.
> > My background is in Scheme/Lisp, and I still find it irritating that I
> cannot
> > just say indent-sexp and the like in Emacs. It is the other properties
> of the
> > language that keep me using it. I also get irritated when I get
> > precedence wrong, so in fact I tend to write (f 1 2) + (g 2 3), which to
> > my eye conveys the intended structure much better and compiles at first
> try.
>
> In languages that don't use curring, you would write
>
> f (1, 2) + g (2, 3)
>
> which also gives application precedence over infix
> operators. So, I think, we can safely say that application
> being stronger than infix operators is the standard
> situation.
[Bryn Keller]
There's another piece to this question that we're overlooking, I
think. It's not just a difference (or lack thereof) in precedence, it's the
fact that parentheses indicate application in Python and many other
languages, and a function name without parentheses after it is a reference
to the function, not an application of it. This has nothing to do with
currying that I can see - you can have curried functions in Python, and they
still look the same. The main advantage I see for the Haskell style is
(sometimes) fewer keypresses for parentheses, but I still find it surprising
at times. Unfortunately in many cases you need to apply nearly as many
parens for a Haskell expression as you would for a Python one, but they're
in different places. It's not:
foo( bar( baz( x ) ) )
it's:
(foo ( bar (baz x) ) )
I'm not sure why folks thought this was an improvement. I suppose it
bears more resemblance to lambda calculus?
> Nevertheless, the currying notation is a matter of habit.
> It took me a while to get used to it, too (as did layout).
> But now, I wouldn't want to miss them anymore. And as far
> as layout is concerned, I think, the Python people have made
> the same experience. For humans, it is quite natural to use
> visual cues (like layout) to indicate semantics.
[Bryn Keller]
Absolutely. Once you get used to layout (Haskell style or Python
style), everything else looks like it was designed specifically to irritate
you. On the other hand, it's nice to have a brace-delimited style since that
makes autogenerating code a lot easier.
Bryn
> Cheers,
> Manuel
>
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