Patryk Zadarnowski wrote [snip]
But there's no guarantee that char is exactly 8 bits wide, is there? So it's appropriate to have separate types, CChar/CSChar/CUChar and Word8/Int8.
No, and neither are there any guarantees about there being *any* specific-width integer types at all! If you're worried about char not being 8 bit, it's likely that the C compiler won't provide an 8 bit integer, either, so Word8/Int8 doesn't solve the problem. [snip]
There is no reason why a Haskell implementation should not provide Word8 or Int8 even if that is not supported by the underlying hardware. Actually I remember doing something like this for MLj (ML for Java). 8 bit words are not provided by the Java Virtual Machine (or at least, weren't then). However they can be provided fairly cheaply. I think I stored them as chars, but for operations treated them as shorts or ints with extra high junk bits. You need to put in extra work to clear the bits when comparing, or doing right shifts, or dividing, but not for addition, subtraction, multiplication, other bit operations, or loading or storing. So it's pretty cheap. Manual wrote [snip]
As I understand it, in ANSI C, the only freedom that an implementation has in choosing a concrete representation for "char" is to decide whether it is signed or unsigned. In any case, it is going to be an 8 bit entity. [snip]
This is false. Look at section 5.2.4.2.1 http://std.dkuug.dk/JTC1/SC22/WG14/www/docs/n843.htm This says only "Their implementation-defined values shall be equal or greater in magnitude (absolute value) to those shown, with the same sign." Thus CHAR_BIT must be at least 8. It may be greater than 8. Also see section 5.2.1. This is the C revision, but I am very sure it was the same with ANSI C.