u128 declaration

[bowenwang1996]

It would be nice if it is possible to do

u128Val: u128 = 1;

but currently this causes the following error

ERROR AS200: Conversion from type 'i32' to 'bignum/integer/u128/u128' requires an explicit cast.

[MaxGraey]

Currently custom type casting not possible in AssemblyScript unfortunately. But you could open issue in AS repo and request such feature)