Flow: Type Inference issue

[alexander-shvets]

In comparison with TypeScript, Flow doesn't catch these errors:

let n = 0
let s = "S"

test(n) // ok
// TypeScript only errors:
test(s)
n += s

let s2 = String()
let n2 = n // inherit type Number
test(n2)  // ok
// TypeScript only errors:
test(s2) 
n2 += s2

function test(n = 0) {}

Why? Is it ideology-based decision?

[jcready]

Since you didn't specifically annotate the test function, flow bases its inference off of the types with which you call it. Flow infers your test function to have the type:

(n?: number | string) => void

[TrySound]

This probably can be closed.
/cc @vkurchatkin

[ShalokShalom]

Type inference not working: We can close this :laughing: