def self.builtins
@builtins ||= Set.new %w(
Add BitAnd BitOr BitXor bool c_char c_double c_float char
c_int clock_t c_long c_longlong Cons Const Copy c_schar c_short
c_uchar c_uint c_ulong c_ulonglong c_ushort c_void dev_t DIR
dirent Div Either Eq Err f32 f64 Failure FILE float fpos_t
i16 i32 i64 i8 isize Index ino_t int intptr_t Left mode_t Modulo Mul
Neg Nil None Num off_t Ok Option Ord Owned pid_t Ptr ptrdiff_t
Right Send Shl Shr size_t Some ssize_t str Sub Success time_t
u16 u32 u64 u8 usize uint uintptr_t
Box Vec String Gc Rc Arc
)
end