refactor: Put all implementations in a single generic

This change eases type inference of return types.

src/Complex/all.ts

@@ -1,8 +1,9 @@
 import {ForType} from '../core/Dispatcher.js'
-import * as Complex from './native.js'
+import {Complex_type, typeImps} from './type.js'
 
-export {Complex}
+export const Complex_bundle = Object.assign({Complex_type}, typeImps())
 
 declare module "../core/Dispatcher" {
-   interface ImplementationTypes extends ForType<'Complex', typeof Complex> {}
+   interface ImplementationTypes<T> extends
+   ForType<'Complex', ReturnType<typeof typeImps<T>>> {}
 }

src/Complex/type.ts

@@ -17,6 +17,8 @@ export const Complex_type = {
    }
 }
 
-export const complex_unary = <T>(dep: Dependency<'zero', [T]>) =>
-   (t: T) => ({re: t, im: dep.zero(t)})
-export const complex_binary = <T>(t: T, u: T) => ({re: t, im: u})
+export const typeImps = <T>() => ({
+   complex_unary: (dep: Dependency<'zero', [T]>) =>
+      (t: T) => ({re: t, im: dep.zero(t)}),
+   complex_binary: (t: T, u: T) => ({re: t, im: u})
+})

src/core/Dispatcher.ts

@@ -11,13 +11,14 @@ type TypeName = string
 type Parameter = TypeName
 type Signature = Parameter[]
 
-export interface ImplementationTypes {}
+export interface ImplementationTypes<T> {}
 export type typeOfDependency = {typeOf: (x: unknown) => TypeName}
 
 // Helper for collecting implementations
 // (Really just suffixes the type name onto the keys of exports)
-export type ForType<T extends string, Exports> = keyof Exports extends string
-   ? {[K in keyof Exports as `${K}_${T}`]: Exports[K]}
+export type ForType<Suffix extends string, Exports> =
+   keyof Exports extends string
+      ? {[K in keyof Exports as `${K}_${Suffix}`]: Exports[K]}
        : never
 
 //dummy implementation for now
@@ -37,6 +38,18 @@ type FinalShape<FuncType> =
 
 type BeginsWith<Name extends string> = `${Name}${string}`
 
+type ImpNames = keyof ImplementationTypes<unknown>
+
+type MatchingParams<Name extends string, Params extends unknown[], T> =
+   {[K in ImpNames]: K extends BeginsWith<Name>
+    ? FinalShape<ImplementationTypes<T>[K]> extends (...args: Params) => any
+       ? Parameters<FinalShape<ImplementationTypes<T>[K]>>
+       : never
+    : never}[ImpNames]
+
+export type BestType<Name extends string, Params extends unknown[]> =
+   Params extends MatchingParams<Name, Params, infer T> ? T : unknown
+
 type DependencyTypes<Ob, Name extends string, Params extends unknown[]> =
    {[K in keyof Ob]: K extends BeginsWith<Name>
     ? FinalShape<Ob[K]> extends (...args: Params) => any
@@ -46,7 +59,7 @@ type DependencyTypes<Ob, Name extends string, Params extends unknown[]> =
 
 export type Dependency<Name extends string, Params extends unknown[]> =
    {[N in Name]:
-    DependencyTypes<ImplementationTypes, N, Params>[keyof ImplementationTypes]}
+    DependencyTypes<ImplementationTypes<BestType<N, Params>>, N, Params>[ImpNames]}
 
 // Now types used in the Dispatcher class itself
 

src/numbers/all.ts

@@ -1,8 +1,13 @@
 import {ForType} from '../core/Dispatcher.js'
-import * as numbers from './native.js'
+import {number_type, typeImps} from './type.js'
+import {arithmeticImps} from './arithmetic.js'
 
-export {numbers}
+export const numbers_bundle =
+   Object.assign({number_type}, typeImps(), arithmeticImps())
 
 declare module "../core/Dispatcher" {
-   interface ImplementationTypes extends ForType<'numbers', typeof numbers> {}
+   interface ImplementationTypes<T> extends
+   ForType<'numbers', ReturnType<typeof typeImps<T>>> {}
+   interface ImplementationTypes<T> extends
+   ForType<'numbers', ReturnType<typeof arithmeticImps<T>>> {}
 }

src/numbers/arithmetic.ts

@@ -1,12 +1,15 @@
 import {configDependency} from '../core/Config.js'
 import {Dependency} from '../core/Dispatcher.js'
 
-export const add = (a: number, b: number) => a + b
-export const unaryMinus = (a: number) => -a
-export const subtract = (a: number, b: number) => a - b
-export const multiply = (a: number, b: number) => a * b
-export const divide = (a: number, b: number) => a / b
-export const sqrt =
+const unaryMinus = (a: number) => -a
+
+export const arithmeticImps = <T>() => ({
+   add: (a: number, b: number) => a + b,
+   unaryMinus,
+   subtract: (a: number, b: number) => a - b,
+   multiply: (a: number, b: number) => a * b,
+   divide: (a: number, b: number) => a / b,
+   sqrt:
    (dep: configDependency
     & Dependency<'complex', [number, number]>) => {
        if (dep.config.predictable || !dep.complex) {
@@ -18,3 +21,4 @@ export const sqrt =
           return dep.complex(0, Math.sqrt(unaryMinus(a)))
        }
     }
+})

src/numbers/type.ts

@@ -4,4 +4,6 @@ export const number_type = {
    from: {string: s => +s}
 }
 
-export const zero = (a: number) => 0
+export const typeImps = <T>() => ({
+   zero: (a: number) => 0
+})