Andrei Alexandrescu wrote:
language_fan wrote:
Wed, 21 Oct 2009 12:35:41 +0200, Pelle Månsson thusly wrote:
Andrei Alexandrescu wrote:
Pelle Månsson wrote:
Jason House wrote:
Andrei Alexandrescu Wrote:
Jason House wrote:
Am I the only one that has trouble remembering how to write an
inline anonymous delegate when calling a function? At a minimum,
both Scala and C# use (args) => { body; } syntax. Can we please
sneak it into D2?
We have (args) { body; }
Andrei
Somehow, I missed that. What kind of type inference, if any, is
allowed? Scala and C# allow omiting the type. Lately I'm doing a lot
of (x) => { return x.foo(7); } in C# and it's nice to omit the
amazingly long type for x. The IDE even knows the type of x for
intellisense... I think scala would allow x => foo(7), or maybe even
=> _.foo(7) or even _.foo(7). I haven't written much scala, so I may
be way off...
Recent experiments by myself indicate you cannot omit the type and you
cannot use auto for the type, so you actually need to type your
VeryLongClassName!(With, Templates) if you need it.
I sort of miss automatic type deduction.
Actually, full type deduction should be in vigor, but it is known that
the feature has more than a few bugs. Feel free to report any instance
in which type deduction does not work in bugzilla.
Andrei
int f(int delegate(int) g) {
return g(13);
}
void main() {
f((auto x) { return x+13; });
}
This does not compile in D v2.034. Am I missing something?
No, in this context the exact type can be inferred unambiguously
without worrying about overloading.
The program should be roughly equivalent with:
int f(int delegate(int) g) {
return g(13);
}
auto __fun(T)(T x) { return x+13; }
void main() {
f(&__fun);
}
which fails with
Internal error: e2ir.c 644
:o)
Can't reproduce that. It doesn't ICE for me. Tried on several DMD
versions. (Doesn't compile, though).
In brief, an untyped function literal should be considered an unbound
template, and as long as type deduction can figure out the types (no
Hindley-Milner, sorry) things should hold water.
Andrei
