On Sat, Feb 04, 2006 at 08:37:51PM +0100, Stefan Holdermans wrote:
Taral wrote:
I think it's very natural. Everything after the $, including other $ expressions, is applied to the stuff before the $. This saves me from a lot of nested parentheses.
To me, ($) helping me to avoid writing lots of parentheses, makes it extremely useful. Actually: except for passing function application to higher-order functions, this is the only way I use it. So, I always thought parentheses were *the* reason for the right- associativity of ($). Not sure if it really was originally, but, ever so, I think it is the best reason.
A left-associative low-precedence application operator can also help avoid writing parentheses, only in different cases, eg. f $$ x + 1 $$ x * x + 2 * x + 1 equals f (x + 1) (x * x + 2 * x + 1) But in this case the parentheses don't nest, which may be a reason why a right-associative version was chosen. ($) helps to avoid the case of nesting parentheses. Such nesting is unbounded, for example you can have chains like this with arbitrary length: a (b (c (d (e (f x))))) even if you only have unary functions. Also, adding or removing a function in such a chain can require non-local changes, that is you are forced to add or remove a closing parenthesis on the end of expression. If you use ($): a $ b $ c $ d $ e $ f x you can easily add or remove a function in the chain. On the other hand, adding new parameters to calls like this f (x + 1) (y - 1) ... is very localised. Best regards Tomasz -- I am searching for programmers who are good at least in (Haskell || ML) && (Linux || FreeBSD || math) for work in Warsaw, Poland