On 09/17/2012 03:53 PM, bearophile wrote:
From this long Reddit post:
http://www.reddit.com/r/haskell/comments/zxcks/haskell_vs_f_vs_scala_a_highlevel_language/c68ybn1
I have seen this linked page:
https://github.com/non/kind-projector
Where it introduces a (fragile) Scala syntax like:
Tuple3[Int, ?, ?]
Eiffel uses this for partial method application.
http://archive.eiffel.com/doc/online/eiffel50/intro/language/tutorial-12.html
That is similar to this D, but it's usable in-place:
template IntFirst3(T2, T3) { alias Tuple!(int, T2, T3) IntFirst3; }
A comparable hypothetical D syntax, for partial template application:
Tuple!(int, ?, ?)
Being it usable in-place, you can use it as:
static asssert(is(Tuple!(int, ?, ?)!(double, float) ==
Tuple!(int, double, float)));
You cannot because multiple ! arguments are disallowed.
Parentheses do not help either because DMDs parser will interpret it as
a deprecated C-style cast expression. (unless this is removed, the
claim that binary '!' makes parsing non-ambiguous is a myth.)
It's a fun syntax: Foo!?
Bye,
bearophile
