function argument accepting function or delegate?

[rsw0x via Digitalmars-d-learn]

On Sunday, 17 January 2016 at 06:27:41 UTC, Jon D wrote:
> My underlying question is how to compose functions taking 
> functions as arguments, while allowing the caller the 
> flexibility to pass either a function or delegate.
>
> [...]

Templates are an easy way.

---
auto call(F, Args...)(F fun, auto ref Args args) { return 
fun(args); }
---
Would probably look nicer with some constraints from std.traits.