One other thing which is semi-relevant, from TDPL:
auto f = (int i) {};
assert(is(f == function));
f seems to be a delegate by default, not a function.
Andrej Mitrovic Wrote:
> The following example should compile according to TDPL. The compiler is
> supossed to automatically infer the type of the parameter in the function
> literal:
>
> void main() { }
>
> T[] find(alias pred, T)(T[] input)
> if (is(typeof(pred(input[0])) == bool))
> {
> for (; input.length > 0; input = input[1 .. $])
> {
> if (pred(input[0]))
> break;
> }
> return input;
> }
>
> unittest {
> int[] a = [1, 2, 3, 4, -5, 3, -4];
>
> // find first negative number
> auto b = find!(function bool(int x) { return x < 0; })(a);
> auto c = find!(function (x) { return x < 0; })(a);
> auto d = find!((x) { return x < 0; })(a);
> }
>
> The auto c and auto d lines are not compiling:
> higher_functions.d(55): Error: template higher_functions.find(alias pred,T)
> if (is(typeof(pred(input[0])) == bool)) does not match any function template
> declaration
> higher_functions.d(55): Error: template higher_functions.find(alias pred,T)
> if (is(typeof(pred(input[0])) == bool)) cannot deduce template function from
> argument types !(__funcliteral2)(int[])
> higher_functions.d(55): Error: template instance errors instantiating template
> higher_functions.d(56): Error: template higher_functions.find(alias pred,T)
> if (is(typeof(pred(input[0])) == bool)) does not match any function template
> declaration
> higher_functions.d(56): Error: template higher_functions.find(alias pred,T)
> if (is(typeof(pred(input[0])) == bool)) cannot deduce template function from
> argument types !(__dgliteral4)(int[])
> higher_functions.d(56): Error: template instance errors instantiating template
>
> Gotta love those error messages, a C++ programmer will feel right at home! ;)
>
> If I add a type specifier like so:
>
> auto c = find!(function (int x) { return x < 0; })(a);
> auto d = find!((int x) { return x < 0; })(a);
>
> Then it will compile. Should I report this to bugzilla?
