Suggestion Backlog Slog, 4/3/2017

[RyanCavanaugh]

"Do crazy stuff while Mohamed is out" edition 👶

• Suggestion: "safe navigation operator", i.e. x?.y #16 Safe Navigation operator
• Support proposed ES Next "::" bind operator #3508 ESNext 'bind' operator ::
• Partial classes  #563 Partial classes
• Allow enums of types other than number #1206 string enums
• Pure annotation in downlevel emits #13721 Pure annotation on downlevel emits
• Allow interfaces to declare protected members and allow implementors to implement protected and private members. #3854 protected in interfaces
• Proposal: Support spread operator for arrays and tuples in function calls #5296 Spread for function calls
• raise a type error on attempt to strict-equal-compare a value of string | null to undefined #14764 Disallow comparing string | null to undefined
• unknown: less-permissive alternative to any #10715 unknown alternative to any
• empty object should be an identity type relative to the intersection operation #14762 T & {} should just be T, at least in typeToString
• Allow to call getter/setter logic When subclassing #338 Allow super.get/set
• Suggestion: Allow declaring class members within a constructor #766 Allow declaring class members in the constructor
• Should unions and non-primitives be allowed for relational comparisons? #5156 > operator and friends on union types
• Inherited typing for class property initializers #10570 Inherited typing for class property initializers
• Cannot Optionalize Class Getters #14417 Optional getters in classes

[RyanCavanaugh]

• Suggestion: "safe navigation operator", i.e. x?.y #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
• Support proposed ES Next "::" bind operator #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
• Partial classes  #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
  • 👎 hasn't happened by now, not going to
• Allow enums of types other than number #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
• Pure annotation in downlevel emits #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
  • 👍 with follow-up on uglify, Daniel to address
• raise a type error on attempt to strict-equal-compare a value of string | null to undefined #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
• empty object should be an identity type relative to the intersection operation #14762 T & {} should just be T, at least in typeToString
  • Filter this out when there no observable effects
  • 👍 (Anders knows what to do)

Out of time

• Allow interfaces to declare protected members and allow implementors to implement protected and private members. #3854 protected in interfaces
• Proposal: Support spread operator for arrays and tuples in function calls #5296 Spread for function calls
• unknown: less-permissive alternative to any #10715 unknown alternative to any
• Allow to call getter/setter logic When subclassing #338 Allow super.get/set
• Suggestion: Allow declaring class members within a constructor #766 Allow declaring class members in the constructor
• Should unions and non-primitives be allowed for relational comparisons? #5156 > operator and friends on union types
• Inherited typing for class property initializers #10570 Inherited typing for class property initializers
• Cannot Optionalize Class Getters #14417 Optional getters in classes