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Hi,
There was a recent discussion regarding suggesting some special algorithms for associative arrays, which made we wonder if the problem isn't actually that it is a slightly annoying when working with ranges of tuples or structs.
For instance you might have code like this
auto a = ["a":5, "b":6];
a.byPair.map!(t=>format!"%s=%s"(t[0],t[1])).writeln;
or
auto r = iota(1,10);
auto gcds = cartesianProduct(r,r).map!(t=>gcd(t[0],t[1]));
which while not too bad isn't as readable as it could be, and it gets worse when the chain gets longer.
With some slight changes to map (which wouldn't be needed if pattern matching exists), one can do this:
import std;
struct MapPrototype(alias f, R) {
R r;
bool empty() { return r.empty; }
auto front() { return f(r.front.tupleof); }
void popFront() { r.popFront; }
auto save() { return typeof(this)(r.save); }
}
auto mapPrototype(alias f, R)(R r) {
return MapPrototype!(f,R)(r);
}
struct Point {
int x;
int y;
}
void main() {
auto r = iota(1,10);
auto gcds = cartesianProduct(r,r).mapPrototype!(gcd);
gcds.writeln;
auto a = ["a":5, "b":6];
a.byPair.mapPrototype!((name,value)=>format!"%s=%s"(name,value)).writeln;
[Point(1,2),Point(3,4)].mapPrototype!((x,y)=>x*x+y*y).writeln;
}
Thoughts?
