-----Original Message----- From: Manuel M. T. Chakravarty [SMTP:chak@cse.unsw.edu.au] Sent: Tuesday, May 22, 2001 6:55 AM To: pk@cs.tut.fi Cc: haskell-cafe@haskell.org Subject: Re: Functional programming in Python

Pertti Kellomäki wrote,

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From: Ketil Malde "Manuel M. T. Chakravarty" writes:

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You want to be able to write

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f 1 2 + g 3 4

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instead of

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(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

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

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? 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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