## Function: SB-ALIEN-INTERNALS:ALIEN-SUBTYPE-P [](../) [](../#function) [](https://github.com/sbcl/sbcl/blob/master/src/code/host-alieneval.lisp/) > Return T iff the alien type TYPE1 is a subtype of TYPE2. Currently, the > only supported subtype relationships are is that any pointer type is a > subtype of (* t), and any array type first dimension will match > (array <eltype> nil ...). Otherwise, the two types have to be > ALIEN-TYPE-=. ### Lambda list ```cl (sb-alien::type1 sb-alien::type2) ```