I'd agree, if the result type was the same as the input type. However, notice that the function I wrote returns an unsigned type, so in the case of byte-sized t

I'd agree, if the result type was the same as the input type. However, notice that the function I wrote returns an unsigned type, so in the case of byte-sized types it would be fn abs(x: i8) -> u8, i.e. there is enough space for 128. Otherwise, good point.