Design Meeting Notes, 7/10/2020

[DanielRosenwasser]

Making tsserver.js a Library

https://github.com/microsoft/TypeScript/pull/39291/files?w=1

• 10% of size of a specific Electron-based editor is TypeScript! Oops!
• Have been looking into producing smaller outputs, but also ways to deduplicate code.
• Modules would fix this, but that's down the road.
• tsserver.js is used for general editing, typescript.js is used for aggregating some data in other contexts - kind of want to consolidate.
• Ideally could use tsserverlibrary.js.
• Seems like one file can call out to another.

Minifying our Outputs

#25658

/ghexp/dtsminify/typescript_dts-minify/lib$ ls -lh tsserver.*
-rw-rw-r-- 1 acasey acasey 8.5M Jul  1 01:17 tsserver.js
-rw-rw-r-- 1 acasey acasey 1.6M Jul  1 01:17 tsserver.js.gz
-rw-rw-r-- 1 acasey acasey 4.6M Jul  1 01:19 tsserver.min.js
-rw-rw-r-- 1 acasey acasey 917K Jul  1 01:19 tsserver.min.js.gz

• Should we do this?
• Can't debug as easily.
• Have to have some sort of way to map back to source.
• Does this actually make sense?
• We really want to fix the "we need to switch to modules" problem.
  • We at least want to reduce download time.
  • We're fine with other people minifying the TypeScript that they ship, but we want to wait on our own infrastructure first.
• Choosing not to minify at this time.

Abstract Constructors and Construct Signatures

#36392

• We already have a pattern that supports mixin factory patterns.
• The problem is that it doesn't work well for abstract classes.
• Not assignable to constructor functions.
• There's a hack to write Function & { prototype: Ctor }, but given class Foo<T> {}, trying to infer from a typeof Foo to Ctor will lose the genericity of Foo.
  • Also accepts non-constructor functions, which isn't exactly desirable.
• Does the output of a mixin function also product an abstract signature?
  • You can manually toggle it with the modifier.
  • But having some sort of class type syntax.
  • Able to model methods that are still marked as abstract.
• Want to get a sense of whether this is interesting to others.
• Still in progress.

Recommended Base TSConfigs

tsconfig/bases#15

• Kind of a DT-like repo that aggregates tsconfigs that we think are good.
• "You say 'recommended' but it fires the wrong neurons for me and makes me mad. My experience with eslint, tslint - the 'recommended' rules make no sense."
• useDefineForClassFields - maybe not great because the emit isn't great.
• skipLibCheck - is that actually good?
• Diverging between tsc --init and tsconfig/recommended
• Lots of options in the team chat that are hard!
  • jsx: react? Sure
  • declaration: true? Okay
  • moduleResolution: node? Sure
  • module: esnext? Uh
  • declarationMap: true?: Okay...
  • incremental: true? Ugh, right, yes.
• recommended might not be a great idea

Default tsc init Options

#39354
#39311