Alternative to std.range.choose

[James Gray]

Is there a better way to achieve behaviour similar to rangeFuncIf
below? f gives a contrived example of when one might want this. g 
is
how one might try and achieve the same with std.range.choose.

import std.stdio;
import std.range : only, chain, join, choose;
import std.algorithm : map;

auto rangeFunctIf(alias F1, alias F2)(bool c)
  if ( __traits(compiles,F1().chain(F2())))
{
    return only(true).repeat(c?1:0).map!(x=>F1()).join
       .chain(only(true).repeat(c?0:1).map!(x=>F2()).join);
}

auto f(ulong n) {
  return (n!=0uL).rangeFuncIf!(()=>only(100/n), ()=>only(0));
}
auto g(ulong n) {
  return choose(n!=0uL,only(100/n),only(0));
}

void main()
{
  writeln(f(2));
  writeln(f(0));
  writeln(g(2));
  //writeln(g(0)); <---- runtime error
}