From ed2ae1b00669bfd3e750e46193c41a042586039f Mon Sep 17 00:00:00 2001
From: Glen Whitney <glen@studioinfinity.org>
Date: Fri, 18 Aug 2023 02:40:05 -0700
Subject: [PATCH] feat: add example of specifying dependencies and signature
 with runtime vals

---
 package.json5             |  2 ++
 pnpm-lock.yaml            | 28 +++++++++++++++++++++++-----
 src/generic/arithmetic.ts | 33 ++++++++++++++++++++++++++++++---
 src/index.ts              | 11 +++++++++++
 src/interfaces/type.ts    |  4 ++--
 tsconfig.json             |  3 ++-
 6 files changed, 70 insertions(+), 11 deletions(-)

diff --git a/package.json5 b/package.json5
index 874d5e3..fcfeb46 100644
--- a/package.json5
+++ b/package.json5
@@ -18,6 +18,8 @@
       url: 'https://code.studioinfinity.org/glen/typocomath.git',
    },
    devDependencies: {
+      '@types/node': '^20.5.0',
+      'source-map': '^0.7.4',
       typescript: '^4.9.3',
    },
 }
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 095704b..76cb316 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -1,14 +1,32 @@
-lockfileVersion: 5.4
+lockfileVersion: '6.0'
 
-specifiers:
-  typescript: ^4.9.3
+settings:
+  autoInstallPeers: true
+  excludeLinksFromLockfile: false
 
 devDependencies:
-  typescript: 4.9.3
+  '@types/node':
+    specifier: ^20.5.0
+    version: 20.5.0
+  source-map:
+    specifier: ^0.7.4
+    version: 0.7.4
+  typescript:
+    specifier: ^4.9.3
+    version: 4.9.3
 
 packages:
 
-  /typescript/4.9.3:
+  /@types/node@20.5.0:
+    resolution: {integrity: sha512-Mgq7eCtoTjT89FqNoTzzXg2XvCi5VMhRV6+I2aYanc6kQCBImeNaAYRs/DyoVqk1YEUJK5gN9VO7HRIdz4Wo3Q==}
+    dev: true
+
+  /source-map@0.7.4:
+    resolution: {integrity: sha512-l3BikUxvPOcn5E74dZiq5BGsTb5yEwhaTSzccU6t4sDOH8NWJCstKO5QT2CvtFoK6F0saL7p9xHAqHOlCPJygA==}
+    engines: {node: '>= 8'}
+    dev: true
+
+  /typescript@4.9.3:
     resolution: {integrity: sha512-CIfGzTelbKNEnLpLdGFgdyKhG23CKdKgQPOBc+OUNrkJ2vr+KSzsSV5kq5iWhEQbok+quxgGzrAtGWCyU7tHnA==}
     engines: {node: '>=4.2.0'}
     hasBin: true
diff --git a/src/generic/arithmetic.ts b/src/generic/arithmetic.ts
index 78ad57d..e00c4e6 100644
--- a/src/generic/arithmetic.ts
+++ b/src/generic/arithmetic.ts
@@ -1,5 +1,32 @@
 import type {Dependencies, Signature} from '../interfaces/type.js'
 
-export const square =
-   <T>(dep: Dependencies<'multiply', T>): Signature<'square', T> =>
-   z => dep.multiply(z, z)
+// This stuff would really go in interfaces/type.js or someplace like that
+type Annotate<U> = U & {dependencies?: Record<string, string>, signature?: string}
+
+function genericImplementation<Deps extends Record<string, string>, Sig extends string>(
+   deps: Deps, sig: Sig, impl: <T>(dep: Dependencies<keyof Deps, T>) => Signature<Sig, T>
+) {
+   const rimpl: Annotate<typeof impl> = impl
+   rimpl.dependencies = deps
+   rimpl.signature = sig
+   return rimpl
+}
+// and of course it would need to be generalized somewhat from the above
+// --------------
+
+// Then here for the implementation we would have:
+export const square = genericImplementation(
+   {multiply: 'T'}, 'square', <T>(dep) => z => dep.multiply(z, z)
+)
+
+// Note this was previously
+
+// export const square =
+//    <T>(dep: Dependencies<'multiply', T>): Signature<'square', T> =>
+//    z => dep.multiply(z, z)
+
+// but then we couldn't get at the dependencies or the signature at runtime. So the point of
+// genericImplementation is that it takes literal values for the dependencies and signature,
+// from which it deduces the types of the actual dependencies of the implementation and the
+// the implementation itself, and then it copies those literal values onto properties of the
+// implementation, where they can be accessed at runtime as illustreated in ../index.ts
diff --git a/src/index.ts b/src/index.ts
index 297b271..397fd7f 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -18,3 +18,14 @@ const myabs = quatAbsquare({re: {re: 0, im: 1}, im: {re:2, im: 3}})
 const typeTest: typeof myabs = 7 // check myabs is just a number
 
 console.log('Result is', myabs)
+
+console.log('Dependencies of square are', Specifications.generic.square.dependencies)
+console.log('Signature of square is', Specifications.generic.square.signature)
+
+const realSquare = Specifications.generic.square<number>({multiply: (a,b) => a*b})
+console.log('Square of 2.5 is', realSquare(2.5))
+
+// and note the following fail with a type error as desired:
+// const fakeSquare = Specifications.generic.square<number>({multiply: (a,b,c) => a*b*c})
+// const stringSquare = Specifications.generic.square<string>({multiply: (a,b) => a*b})
+// console.log('Square of three is', stringSquare('three'))
diff --git a/src/interfaces/type.ts b/src/interfaces/type.ts
index 9e6870d..7dbf276 100644
--- a/src/interfaces/type.ts
+++ b/src/interfaces/type.ts
@@ -68,8 +68,8 @@ export interface Signatures<T> {
 
 type SignatureKey<T> = keyof Signatures<T>
 
-export type Signature<Name extends SignatureKey<T>, T> = Signatures<T>[Name]
+export type Signature<Name, T> = Signatures<T>[Name & SignatureKey<T>]
 export type Returns<Name extends SignatureKey<T>, T> = ReturnType<Signatures<T>[Name]>
-export type Dependencies<Name extends SignatureKey<T>, T> = {[K in Name]: Signature<K, T>}
+export type Dependencies<Name, T> = {[K in Name & SignatureKey<T>]: Signature<K, T>}
 
 export type AliasOf<Name extends string, T> = T & {aliasOf?: Name}
diff --git a/tsconfig.json b/tsconfig.json
index aae3a94..b45999b 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -2,6 +2,7 @@
     "compilerOptions": {
         "target": "ES2022",
         "rootDir": "./src",
-        "outDir": "./obj"
+        "outDir": "./obj",
+        "moduleResolution": "nodenext"
     }
 }