JuliaLang/julia — comment on commit 3fe744604c9a96a9a0eee8f26d0fd169e40c8449
File:  line 0
By JeffBezanson:

It's just like $ actually; it's syntactic (not a function call) when used as a unary operator, and for now it will only do anything inside ccall, just like $x only does something inside quote.