On Fri, Oct 30, 2015 at 8:29 AM, FANG Colin <colinf...@gmail.com> wrote: > I have got the same confusion. Any ideas? > > I have even seen usage of A = T (no const) > (http://docs.julialang.org/en/release-0.4/manual/types/#type-unions), is it > supposed to be bad (slow) because it is a global variable? >
no const will have performance issue since it's a global. `const A = T` is what `typealias A T` lowered to when it doesn't have type parameters. In this case, it's just a matter of style. Being consistent within a file is probably better but you can pick whichever you prefer. > > > On Thursday, November 6, 2014 at 3:38:41 PM UTC, Steven G. Johnson wrote: >> >> Given a type T, what is the difference in practice between >> typealias A T >> and >> const A = T >> ? >> >> There seems to be some disagreement over which one to use (e.g. >> https://github.com/JuliaLang/Compat.jl/commit/8211e38ac7d8448298a2bb3ab36d6f0b6398b577). >> >> My impression is that there is no difference, and that the only advantage >> of a typealias is that it can be parameterized. Is that right? >> >> If they are equivalent, what is the Julian style? Even in Julia Base it >> doesn't seem to be entirely consistent.
