Why doesn't D have a in keyword for arrays? The docs explains that you can use in only for associative arrays but I don't see the reasons for such decision. Example code: void main() { auto v = ["r", "i", "o"]; assert ("r" in v); } That currently fails: main.d(4): Error: incompatible types for (("r") in (v)): 'string' and 'string[]'