From 171b6941f42f680062e0531a3503f8e155817ed8 Mon Sep 17 00:00:00 2001
From: Glen Whitney <glen@studioinfinity.org>
Date: Sun, 31 Jul 2022 10:01:20 -0700
Subject: [PATCH] refactor: add stub for instantiating the template

---
 src/core/PocomathInstance.mjs | 30 +++++++++++++++++++++++-------
 1 file changed, 23 insertions(+), 7 deletions(-)

diff --git a/src/core/PocomathInstance.mjs b/src/core/PocomathInstance.mjs
index 62c6757..4fc7b5b 100644
--- a/src/core/PocomathInstance.mjs
+++ b/src/core/PocomathInstance.mjs
@@ -7,6 +7,14 @@ const anySpec = {} // fixed dummy specification of 'any' type
 
 const theTemplateParam = 'T' // First pass: only allow this one exact parameter
 
+/* Returns a new signature just like sig but with the parameter replaced by
+ * the type
+ */
+function substituteInSig(sig, parameter, type) {
+   const pattern = new RegExp("\\b" + parameter + "\\b", 'g')
+   return sig.replaceAll(pattern, type)
+}
+
 export default class PocomathInstance {
    /* Disallowed names for ops; beware, this is slightly non-DRY
     * in that if a new top-level PocomathInstance method is added, its name
@@ -413,15 +421,22 @@ export default class PocomathInstance {
             }
          }
          if (explicit) {
-            this._addTFimplementation(
-               tf_imps, rawSignature, behavior.uses, behavior.does)
+            this._addTFimplementation(tf_imps, rawSignature, behavior)
             continue
          }
          /* It's a template, have to instantiate */
-         /* But just for initial testing, punt and use T as synonym for 'any' */
-         const signature = rawSignature.replaceAll(theTemplateParam, 'any')
-         this._addTFimplementation(
-            tf_imps, signature, behavior.uses, behavior.does)
+         /* First, add the known instantiations */
+         if (!('instantiations' in behavior)) {
+            behavior.instantiations = new Set()
+         }
+         for (const instType of behavior.instantiations) {
+            const signature =
+                  substituteInSig(rawSignature, theTemplateParam, instType)
+            this._addTFimplementation(tf_imps, signature, behavior, instType)
+         }
+         /* Now add the catchall signature; for now, punting on the behavior */
+         const signature = substituteInSig(rawSignature, theTemplateParam, 'any')
+         this._addTFimplementation(tf_imps, signature, behavior)
       }
       const tf = this._typed(name, tf_imps)
       Object.defineProperty(this, name, {configurable: true, value: tf})
@@ -432,7 +447,8 @@ export default class PocomathInstance {
     * to typed-function implementations and inserts the result into plain object
     * imps
     */
-   _addTFimplementation(imps, signature, uses, does) {
+   _addTFimplementation(imps, signature, behavior, instType) {
+      const {uses, does} = behavior
       if (uses.length === 0) {
          imps[signature] = does()
          return