How to translate this macro to Adept?

[ghost]

#define iup_isshift(_s) (_s[0]=='S')

C macros are typeless, so we have to guess the type of _s. I guess it's *ubyte. But I have no idea why this doesn't work:

func iup_isshift(_s *ubyte) bool = (_s[0]=='S')

The compiler always said error: Incompatible types 'ubyte' and '*ubyte'

Update: I figured it out, I'm missing ub suffix. This worked:

func iup_isshift(_s *ubyte) bool = (_s[0]=='S'ub)