[Suggestion] Inferring for array literals

[MaxGraey]

Currently all array declarations require also its type like:

let arr: i32[] = [1, 2, 3];
// or
let arr = <i32[]>[1, 2, 3]; // or as i32[]

In one hand this follow the “explicit is better than the implicit” philosophy, in other hand this complicates porting and refactoring. Even Rust has ability to infer such array literals. So will be great have a choice.

So my suggest follow next infer rule: array's element types infer from first element of array (similar to Rust). But also allow null for references in any places:

let arr1 = [1, 2, 3]                   // -> arr1: i32[]
let arr2 = [1.0, 0, 2]                 // -> arr2: f64[]
let arr3 = [0x7FFFFFFF_FFFFFFFF, 0, 1] // -> arr3: i64[]
let arr4 = [2.0 as f32, 0, 2]          // -> arr4: f32[]
let arr5 = [NaN]                       // or Infinity -> arr5: f64[]
let arr6 = ["abc", null]               // -> arr6: (string | null)[]
let arr7 = [null, "abc"]               // -> arr7: (string | null)[]
let arr8 = []                          // compile error!
let arr9 = [null]                      // compile error!
let arr10 = [1, null]                  // compile error currently. But may possible in the future
let arr11 = [1, NaN]                   // compile error!

[MaxGraey]

Closed due to #1021 merged