optimization of list comprehensions
Tue Mar 7 12:17:11 CET 2006
Richard A. O'Keefe wrote:
> [deleted stuff]
i can only say that i agree wholeheartedly with this.
> Now we actually have three things we are discussing here:
> - list comprehensions (and why don't we have tuple comprehensions?
> Clean has them, and I use them a lot when writing Clean)
> We have them in Erlang, because of Mnemonsyne.
> - list walking for side effect (not needed in Haskell because there
> aren't any side effects)
> We can get this effect simply by sticking "_ =" in front of a
> list comprehension (or any other variable name that is clearly
> not intended to be used again) and having a very slightly smarter
> compiler. I _hope_ it would not be very useful.
> - list folding (and again, tuple folding would be nice too)
> Presumably one of the reasons that Haskell doesn't have this is
> that Haskell has at least four different versions of fold
> This one certainly would be useful; the OTP sources could use some
> kind of fold at least 400 times, and foldl at least 300 times.
> I think it would be advisable to check several hundred potential
> uses of the notation before designing a concrete syntax.
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