experiment inferring TS types from a JS template

This commit is contained in:
Jos de Jong 2022-12-24 20:17:36 +01:00
parent a5848125e4
commit 11792e0435

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src/infer.ts Normal file
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/**
* Idea: instead of writing TypeScript, and inferring the JS-pocomath signature
* from TS that via a TypeScript plugin, we can maybe do this the other way
* around: take the JS-pocomath signature as base (and source of truth), and
* infer TypeScript interfaces from that using infer in template literal types.
*/
type T = {} // TODO: how to do generics?
const create = createFactory<{
number: number
bigint: bigint
T: T // TODO: how to do generics?
'Complex<T>': unknown // TODO: how to do generics?
}>()
// TODO: how to pass config?
// FIXME: multiple signatures do not work
const createSquare = create({
multiply: '(number, number) : number',
// zero: '(number) : number'
},dep => {
return (x: number) => dep.multiply(x, x)
}
)
// the code works in JS, and works in TS
const multiply = (a: number, b: number) => a * b
const square = createSquare({ multiply })
console.log('square', square(8)) // 64
function createFactory<BaseTypes extends Record<string, unknown>>() {
type K = string & keyof BaseTypes
type ResolveType<T extends K> = BaseTypes[T]
type ResolveTuple<T> =
T extends K ? [ResolveType<T>] :
T extends `${infer L extends K}, ${infer M extends K}` ? [ResolveType<L>, ResolveType<M>] :
T extends `${infer L extends K}, ${infer M extends K}, ${infer N extends K}`
? [ResolveType<L>, ResolveType<M>, ResolveType<N>]
: never
type ResolveFunction<T> =
T extends `${infer Name}(${infer Args}) : ${infer L extends K}`
? (...args: ResolveTuple<Args>) => ResolveType<L>
: never
return function create<T extends string, U extends string, V>(
dependencies: { [L in T]: U },
callback: (deps: { [L in T]: ResolveFunction<U> }) => V
) {
return callback
}
}