Add 'argument mode adapter' functions to std

[brson]

So we have a bunch of higher order functions, that usually take functions with generic, by ref parameters; then we have a bunch of standard utility functions in std::int etc that take their arguments by value.

Both those are the correct decisions individually, but they can't be composed together:

// no-worky
vec::foldl(int::sub, 0, [1,2,3]);

We could have a function that takes it's arguments by ref and calls another function by value:

fn cp_ref2<T, U, V>(&&a: T, &&b: U, f: block(+a: T, +b: U) -> V) -> V { f(a, b) }

With which you could

vec::foldl(bind cp_ref2(_, _, int_sub), 0, [1,2,3]);

If this is a good idea, then identify a bunch of useful scenarios and write these functions, maybe in std::util.

[brson]

These little functions like uint::add, sub, eq, lt, etc. really only exist to compose with other functions. Maybe it would make more sense to have them take references.

[Dretch]

IMHO:

vec::foldl({|a, b| int::sub(a, b)}, 0, [1,2,3]);

is prettier than:

vec::foldl(bind cp_ref2(_, _, int_sub), 0, [1,2,3]);

[brson]

And with future syntax changes it will probably even be vec::foldl(|a, b| sub(a, b), 0, [1,2,3]). That's pretty good.

[brson]

And argument modes are going away, so I think this can close.