subtyping for map/seq

[akashlal]

When a value of type map[any,any] is cast to a variable of type map[int,int] does this involve checking if every key and value present in the map can be cast to int? Or does the cast happen immediately but the next time one reads the map, the cast is done then?

[shazqadeer]

The cast check happens immediately. Note that the cast check is emitted only in the generated Zing code and not in the generated C code.