type inference with if-return

[unional]

TS (1.9.0-dev.20160407)

Don't know if this is possible 🌹 :

function working(param: string | string[]) {
  if (typeof param === "string") {
    // param is string
  }
  else {
    // param is string[]
  }
}

function notWorking(param: string | string[]) {
  if (typeof param === "string") {
    // param is string
    return;
   }

   // param is string | string[]
   // Can it be detected and inferred as string[] here?
}

[basarat]

This is already done as a part of the code flow analysis that Anders is doing (not on master yet) 🌹

[RyanCavanaugh]

See #2388

[basarat]

@unional PR is up if you want to watch for the moment it getting merged : #8010 (comment) 🌹