Common Criticisms

Nim doesn't require call-site annotation for var parameters

This is referring to systems like C#'s: void foo(ref int myInput){...}; foo(ref a);. Note the ref on the foo call. If this was Nim, it'd be impossible to tell from the call-site that foo has the potential to modify a.

** * NOTE * ** : The following is wrong, I'll fix it soon

Possibly. The problem here is that of perception. In many languages, heap allocation through pointers is the only method of having objects, and passing them to a function gives the freedom to modify them. In Nim, things can be allocated on the stack, and those things need to be treated in the same way as things on the heap.

proc foo(input: var T) = ...
let a: ref T = ...
foo(a)  # valid, this is Java-style
var b: T = ...
foo(b)  # also valid and equivalent

Note that the difference between what happens in Java and what Nim does is simply a matter of efficiency: Nim does not require our T to be allocated on the heap, and it certainly allows b to be declared with let, which will force an compile-time error to be thrown.