Dispatch function based on value of parametric type

[Ralph_Smith]

@mohamed82008

Note that when you make some field a type parameter, you can no longer enforce its type to be a subtype of Integer for example

You could validate in an inner constructor:

struct BustedType2{B,S}
    function BustedType2{B,S}() where {B,S}
        (isa(B,Bool) && isa(S,Integer)) || error("bad params")
        new()
    end
end