Typescript: Suggestion Backlog Slog, 8/22/2018

[RyanCavanaugh]

• #25172 Narrowing unknown with === or friends
• #24193 null should be an allowable discriminant value
• #26075 Should type.isLiteral() return true for boolean literals?
• #22631 Named type arguments
• #26572 Destructuring computed private class property names
• #10178 Access UMD globals from modules
• #14951 Index signatures on fresh object literals
• #26015 Even stricter class property initialization
• #26404 Scrape MDN for DOM/core documentation comments
• #26193 esModuleInterop should enable allowSyntheticDefaultImports
• #7481 "soft" type assertion operator
• #24350 Should array literals be tuples?
• #23689 "invalid" type

[RyanCavanaugh]

• #25172 Narrowng unknown with === or friends
  
  
  
  • OP is not super compelling
    
    
    
    
    
    • If you have a known RHS, why aren't you using the RHS?
    
    
    
  
  
  • Last case with Response is more compelling
    
    
    
    
    
    • Reminder that minimal examples often lose their compellingness
    
    
    
  
  
  • :+1: assuming no bad side effects
  
  
• #24193 null should be an allowable discriminant value
  
  
  
  • Comes up with node packages a lot
  
  
  • Didn't we do something here recently?
    
    
    
    
    
    • Allowing mixed-unit-type discriminants?
    
    
    
  
  
  • Treat null as a primitive for the purpose of detecting discriminated unions
  
  
  • :+1:
  
  
• #26075 Should type.isLiteral() return true for boolean literals?
  
  
  
  • Yes!
  
  
• #22631 Named type arguments
  
  
  
  • No
  
  
• #26572 Destructuring computed private class property names
  
  
  
  • :+1: stop the madness, Won't Fix this bug
  
  
  • Daniel will add a testcase
  
  
• #10178 Access UMD globals from modules
  
  
  
  • Open question: If you import from that module, is it poisoned then ?
    
    
    
    
    
    • NOBODY CARES
    
    
    
  
  
  • No satisfactory workaround because there's no namespace import
  
  
  • What do we call this flag?
    
    
    
    
    
    • Bikesheeeeeed
    
    
    
  
  
  • :+1:
  
  
• #14951 Index signatures on fresh object literals
  
  
  
  • It's clever? Or is it. Definitely!
  
  
  • Proposal: Fresh object literals get an index signature that widens away
    
    
    
    
    
    • Kind of expensive and weird
    
    
    
  
  
  • Proposal: Do something special when indexing an object literal
    
    
    
    
    
    • Walk through numeric/string names as appropriate and make a union with undefined
    
    
    
    • Cheap and targeted
    
    
    
  
  
  • :+1:
  
  
• #26015 Even stricter class property initialization
  
  
  
  • Can't break the world - yet another flag
  
  
  • Effectively a syntactic enforcement
  
  
  • The control flow checker is kind of half-off in this case
  
  
  • :-1:
  
  
• #26404 Scrape MDN for DOM/core documentation comments
  
  
  
  • :+1: Community
  
  
• #26193 esModuleInterop should enable allowSyntheticDefaultImports
  
  
  
  • :+1: sure
  
  
• #7481 "soft" type assertion operator
  
  
  
  • Desired: "as" with one-way assignability semantics but still have contextual typing
  
  
  • What terrible operator name would we come up with?
  
  
  • We could use Flow's type assertion syntax - it's reserved
  
  
  • We want it but all available syntax (cough) is terrible
  
  
  • Needs a super clever syntactic insertion point
  
  
  • Related: Block-syntax type assertion
    
    
    
    
    
    • Speculating on how to make this happen in a performant way
    
    
    
  
  
  • Keep noodling on it
  
  
• #24350 Should array literals be tuples?
  
  
  
  • Is the breakage not as bad as we thought?
  
  
  • General literal-assertion problem
    
    
    
    
    
    • Literal types are really problematic today
    
    
    
    • What would a smarter world look like?
    
    
    
  
  
  • ! should be the "do the other thing" operator?
    
    
    
    
    
    • ... no
    
    
    
  
  
  • We shouldn't hurt non-tuple-users to help tuple users, arguably
  
  
  • Keep noodling on it
  
  

[mmkal]

@RyanCavanaugh what about https://github.com/Microsoft/TypeScript/issues/23689?? There doesn't seem to be a 👍 or 👎 for it (very much hoping for 👍)!