Comment #0 by bearophile_hugs — 2012-05-24T14:40:11Z
std.functional.curry doesn't work if the first argument (the curried one) is a function. This is a common enough use case:
import std.functional;
auto foo(T)(T function(T x) f, T x) {
return f(x);
}
int bar(int x) { return x * 2; }
alias curry!(foo, &bar) fooBar;
void main() {}
DMD 2.060alpha gives:
temp.d(6): Error: expression & bar is not a valid template value argument
temp.d(6): Error: template instance std.functional.curry!(foo,& bar) error instantiating
I think D functional-style programming needs a more flexible/uniform currying.
Workaround:
import std.traits: ParameterTypeTuple;
auto foo(alias F)(ParameterTypeTuple!F[0] x) {
return F(x);
}
int bar(int x) { return x * 2; }
alias foo!bar fooBar;
void main() {
assert(fooBar(5) == 10);
}
But this is not as flexible. A language that supports functional programming needs to handle functions as first class citizens.
Comment #1 by robert.schadek — 2024-12-01T16:15:08Z