On Sun, 9 Sep 2007, Peter Verswyvelen wrote:
I find it unfortunate that one can't (I guess) define custom unary operators in Haskell.
Why? What is your application? In fact, alphanumeric identifiers are used as unary operators.
Is this correct? If so, is this just because eg (* 100) declares a function that partially applies the * operator, so this syntax disallows unary operators? Could this be fixed by introducing a different syntax for partial operator application? E.g. (? * 100) instead of just (*100)?
You can also use "special syntax" for having unary operators. E.g. (*) :: () -> a -> a used as ()*100 :-)
This would also fix the ambiguity between (-10) as being either the number minus 10 or the "subtract by 10' function.
There has been a long discussion whether the unary minus belongs to number literals or not. http://www.haskell.org/pipermail/haskell-cafe/2006-September/017941.html I think that the benefits of prefix or postfix symbolic operators were not worth dispensing with the comfortable section syntax.