[phkahler]

IMHO it is total fail to have int be dependent on the machine architecture. C99 fixed this behavior with types for specific sizes so people could finally write portable code. Julia should adopt 64bit integers by default given its intended audience and the reality that even some phones have 64bit processors. int64_t works on 32bit processors too, but with a performance penalty. Having the range of a variable depend on the machine architecture really went out of style a long time ago.

[StefanKarpinski]

We considered that, but even though 64-bit ints work on 32-bit machines, they are dog slow. Insisting that integers are 64-bit everywhere is basically saying that you want slow for loops, slow array indexing – slow everything – on 32-bit systems. Clearly that's unacceptable in a language that is meant to be fast. So Julia has Int32 and Int64 when you want a specific bit size and Int is always the same size as your pointers. This arrangement is considerably simpler to deal with than C's "integers are whatever size I want them to be! [evil cackle]" approach. In particular, default integers and pointers are always the same size – which is not always the case in C (I'm looking at you, Win64) – so there's only one system-dependent size to worry about.