Brian Hulley wrote:
Jared Updike wrote:
[a,b,c ; tail] === a :: b :: c :: tail -- where ::
How is [a,b,c ; tail] simpler, clearer or less typing than a:b:c:tail ? I think that the commas and semicolons are easy to confuse.
It seems strange that you can write [a,b,c] with a nice list sugar but if you want to include a tail you have to switch to the infix notation using list cons. Prolog for example allows you to write [a,b,c|Tail] but neither Haskell nor ML allows this. In Haskell, | is used to introduce a list comprehension so I was just trying to find a replacement symbol for when you want the equivalent of the Prolog list sugar so that you wouldn't be forced to use infix notation.
All this was not to replace a:b:c:tail but was to replace a::b::c::tail so that : could be used for type annotations instead.
There is the .. operator which is unused in pattern matching contexts. So maybe case [1,3..] of [a,b,c,tail..] -> tail -- I like this one, the ..] catches the eye better [a,b,c,..tail] -> tail -- I think this is less clear at a glance [a,b,c,..tail..] -> tail -- I expect no one to like this [a,b,c,_..] -> [a,b,c] -- Not the best looking thing I've ever seen [a,b,c,.._] -> [a,b,c] -- ditto [a,b,c,.._..] -> [a,b,c] -- ick But this implies [a,b,c,[]..] is the same as [a,b,c] and [a,b,c,[d,e,f]..] is the same as [a,b,c,d,e,f] and [a,b,c,[d,e,f..]..] is [a,b,c,d,e,f..] Wacky.