Typescript: Suggestion Backlog Slog, 8/6/2018

Created on 6 Aug 2018 · 3Comments · Source: microsoft/TypeScript

#5453 Variadic kinds - what use cases remain here?
#26234 Disallow truthy checks of void
#5203 Disallow OOB access on tuples
#5863 Static polymorphic this
#23005 T[K] should be never when K is never
#22892 string enum object should be indexable type
#22851 esModuleInterop should work when target = esnext
#22815 Abstract classes that implement interfaces shouldn't require method signatures
#22806 Partial<T> should be a weak type
#22769 Allow unshadowed parameter initializer references in ES6+
#22759 Let JSX children be subject to tupleness
#22709 Allow references to literal-ish-initialized enums in type positions
#22669 Add a new overload to Function#bind
#22665 Add a mode to make TS act like JS
#22649 Combine tsconfig with file list
#22610 Keep infer variable in scope in false arm of conditional type
#22609 Do some type guards based on overload when a good discriminant is present
#22605 Provide a back-compat mechanism for bundled .d.ts files in package.json
#22598 Allow speculative union type property access in typeof (expression) operands
#22509 Something something mapped types
#22311 Error on out-of-scope literal assigned to enum
#22230 Allow implicit undefined->0 coercion under strictNullChecks for bitwise ops
#22208 Prefer .d.ts over .ts if it's in files array
#26136 Arg union type inference for overloads
#26129 Forbid illogical generic declarations

Design Notes

Source

RyanCavanaugh

Most helpful comment

Well, it's accepted
Wondering if actionable
We're imitating ActionScript

RyanCavanaugh on 7 Aug 2018

😄8

All 3 comments

#5453 Variadic kinds
- Currently we allow you to capture tuples in variadic rest positions
- But the tuples themselves cannot contain rests
- This would allow deconstruction of tuples
- What functions would be typable with this that currently aren't?
- Promisify
- Should we close holes that allow people to write trivial turing machines in the type system?
- ??
#26234 Disallow testing void exprs
- Breaking change
- All goodness
- Found bugs in us and VS Code
- Found "type errors" in a couple other projects
#5203 OOB on tuples should be errors
- :+1:
#5863 Polymorphic this
- Static inheritance in signatures is plainly unsound
- So calls to the polymorphic this are right out
- Isn't what people want just the non-signature side?
- Do people want instance-this or static-this ?
- Representation vs checking
- Discuss soundness
#23005 T[K] should be never
- :+1:
#22892 String enums should be indexed types
- Our dot behavior makes this a bad idea
#22815 Interface members in abstract classes
- Should we copy them automatically?
- It's presumably what you want
- What happens to optional members?
- They become... abstract optional? What is that even?
  - How do you not-implement an optional abstract member?
- Need to avoid hop-skip-jump problem
- Post some questions on this
#22806 Partial<T> should be weak?
- It is
- Weak checking applies to assignability, not comparability
- WIA
#22769 Parameter initializers
- Allow in ES6, error in downlevel only
#22759 Allow tuples in JSX children
- :+1:
#22709 Enum literals
- There are actually many kinds of enums under the hood
- Union enums only get created when only bare literals (or nothing) are initializers
- These kinds of enums behave differently
- You might want one or the other and this is how you choose
- WIA; would be a BC
#22311 Out-of-range enum assignment
- Back compat problem
- Not really a trap
- Problem for e.g. mod flags
- Maybe disallow in strict
#22230 undefined/null in & / |
- :-1:
#26136 Inference of unions from argument lists
- Would this imply filtering if you weren't capturing the whole argument list?
- No (spreading back would be a nightmare)