Programmatic generation of curried interfaces for custom kinds

[MajorLift]

Current example output

// outputInterfaces(name: string, numParams: number): InterfaceDeclaration[]
[
  'export interface ExampleKind extends Kind.Kind {\n' +
    '    f(x: Type._$cast<this[Kind._], unknown>): ExampleKind_T1<typeof x>;\n' +
    '}',
  'interface ExampleKind_T1<X1 extends unknown> extends Kind.Kind {\n' +
    '    f(x: Type._$cast<this[Kind._], unknown>): ExampleKind_T2<X1, typeof x>;\n' +
    '}',
  'interface ExampleKind_T2<X1 extends unknown, X2 extends unknown> extends Kind.Kind {\n' +
    '    f(x: Type._$cast<this[Kind._], unknown>): ExampleKind_T3<X1, X2, typeof x>;\n' +
    '}',
  'interface ExampleKind_T3<X1 extends unknown, X2 extends unknown, X3 extends unknown> extends Kind.Kind {\n' +
    '    f(x: Type._$cast<this[Kind._], unknown>): _$exampleKind<X1, X2, X3, typeof x>;\n' +
    '}'
]

Progress

• Generates InterfaceDeclarations with correct naming scheme (e.g. _T1, _T2), ordering, and function signatures.
• Inject type constraints for all parameters (currently defaults to unknown).
  • Dynamically generate factory code,
  • OR update interface declaration with ts-morph.
• Import hkt-toolbelt submodules required to express type constraints.
• Access existing _$ implementation.
  • Stringify and inject into source file,
  • OR import from separate module.
• Emit/output as a module that can be used locally without further configuration.

References

• Closes Research programmatic generation of custom kinds with AST manipulation #61

[poteat]

I love this! This is a really good idea for ensuring the codebase is consistent. I wonder if there isn't a TS Hygienic Macro framework or extension that we could utilize? That would mean we could separate out the "abstraction" of using code to generate code onto the macro system.

[MajorLift]

Good to hear that you agree this could be useful!

It looks like there aren't that many options for TypeScript macros, and this is pretty much the only one that's being actively maintained: https://github.com/GoogleFeud/ts-macros.

It does look pretty promising, and there's even a playground, which should make it easy to experiment with: https://googlefeud.github.io/ts-macros/. I'll look into whether we can use it for this PR.