Typescript: Suggestion Backlog Slog, 4/3/2017

[RyanCavanaugh]

"Do crazy stuff while Mohamed is out" edition 👶

• #16 Safe Navigation operator
• #3508 ESNext 'bind' operator ::
• #563 Partial classes
• #1206 string enums
• #13721 Pure annotation on downlevel emits
• #3854 protected in interfaces
• #5296 Spread for function calls
• #14764 Disallow comparing string | null to undefined
• #10715 unknown alternative to any
• #14762 T & {} should just be T, at least in typeToString
• #338 Allow super.get/set
• #766 Allow declaring class members in the constructor
• #5156 > operator and friends on union types
• #10570 Inherited typing for class property initializers
• #14417 Optional getters in classes

[RyanCavanaugh]

• #16 Safe Navigation operator
  
  
  
  • Not at stage 2 yet; behavior may differ
  
  
  • We have opinions on null and undefined coalescing
  
  
  • Ryan wants us to be ahead rather than behind on features
  
  
  • Not even in Babel yet?
  
  
  • Even stage 2 isn't safe (decorators!)
  
  
  • Start work at stage 2; stage 1 is too early
  
  
  • Let's wait until stage 2
  
  
• #3508 ESNext 'bind' operator ::
  
  
  
  • Very important open questions on semantics, which may differ widely in behavior
  
  
  • Exact binding location is unclear
  
  
  • Wait for stage 2
  
  
• #563 Partial classes
  
  
  
  • Sugar for existing syntax, sometimes
  
  
  • Not part of ES6
  
  
  • Trying to avoid new ES6 class features
  
  
  • We're not trying to reinvent C# as much as people like to pretend otherwise
  
  
  • The side effects of this with modern modules are simply bad
  
  
  • JavaScript has better compositional patterns available
  
  
  • :-1: hasn't happened by now, not going to
  
  
• #1206 string enums
  
  
  
  • Everyone wants them
  
  
  • They're awesome
  
  
  • Come on
  
  
  • What about taking enums to TC39?
  
  
  • Sugar for what we can already do
  
  
  • We keep saying "Don't use namespace because modules are better" but then use namespaces for all would-be sugar features
  
  
  • Another sketch
  
  

 enum Foo {
    Red = "Red is my Favorite Color",
    Green = "Green is my Favorite color",
    Blue = "Blue!"
}

namespace Foo {
    export const Red: "Red" = "Robin";
    export type Red = typeof Red;
    export const Blue: "Blue" = "Bluebird";
    export type Blue = typeof Blue;
}
// "Robin" | "Bluebird"

type Foo = Foo.Red | Foo.Blue;

• Ryan to write minispec
  
  
  
  • #13721 Pure annotation on downlevel emits
  
  
  • Needed for good treeshaking
  
  
  • Wouldn't emit if it had static non-literal initializers
  
  
  • Debate about terminology
  
  
  • Want to emit something understood by both uglify and closure
  
  
  • Why don't minifiers just recognize this pattern?
    
    
    
    
    
    • Not enough resources, requires a lot of CFA
    
    
    
  
  
  • We could just write /* class */ and the minifiers have to figure out side effects
  
  
  • :+1: with follow-up on uglify, Daniel to address
  
  
  • #14764 Disallow comparing string | null to undefined
  
  
  • Currently a hack
  
  
  • It's all ad hoc
  
  
  • Proposed rule: You can't test for the "wrong" empty
  
  
  • Checking for undefined is good defensiveness, checking for null is suspicious
  
  
  • AMF
  
  
  • #14762 T & {} should just be T, at least in typeToString
  
  
  • Filter this out when there no observable effects
  
  
  • :+1: (Anders knows what to do)
  
  

Out of time

• #3854 protected in interfaces
• #5296 Spread for function calls
• #10715 unknown alternative to any
• #338 Allow super.get/set
• #766 Allow declaring class members in the constructor
• #5156 > operator and friends on union types
• #10570 Inherited typing for class property initializers
• #14417 Optional getters in classes