From a5914076b049ef086088c0d9604d949f84745162 Mon Sep 17 00:00:00 2001
From: Scott Richmond <kredati@users.noreply.github.com>
Date: Wed, 18 May 2022 19:35:41 -0400
Subject: [PATCH] Interpret loop/recur

---
 src/ludus/interpreter.clj | 44 +++++++++++++++++++++++++++++++--------
 1 file changed, 35 insertions(+), 9 deletions(-)

diff --git a/src/ludus/interpreter.clj b/src/ludus/interpreter.clj
index bf2ab89..352b70c 100644
--- a/src/ludus/interpreter.clj
+++ b/src/ludus/interpreter.clj
@@ -248,9 +248,8 @@
                  {::data/struct true ::data/type ::data/ns ::data/name name}
                  (map-values #(interpret-ast % ctx))
                  members)]
-        (do
-          (vswap! ctx update-ctx {name ns})
-          ns)))))
+        (vswap! ctx update-ctx {name ns})
+        ns))))
 
 (defn- interpret-import [ast ctx]
   (let [path (:path ast)
@@ -277,6 +276,33 @@
       (vswap! ctx update-ctx {name ref})
       ref)))
 
+(defn- interpret-loop [ast ctx]
+  (let [tuple (interpret-ast (:expr ast) ctx)
+        clauses (:clauses ast)]
+    (loop [input tuple]
+      (let [output (loop [clause (first clauses)
+                          clauses (rest clauses)]
+                     (if clause
+                       (let [pattern (:pattern clause)
+                             body (:body clause)
+                             new-ctx (volatile! {::parent ctx})
+                             match? (match pattern input new-ctx)
+                             success (:success match?)
+                             clause-ctx (:ctx match?)]
+                         (if success
+                           (do
+                             (vswap! new-ctx #(merge % clause-ctx))
+                             (interpret-ast body new-ctx))
+                           (recur (first clauses) (rest clauses))))
+      
+                       (throw (ex-info (str "Match Error: No match found in loop for " input) {}))))]
+        (if (::data/recur output)
+          (recur (:tuple output))
+          output
+          ))
+      ))
+  )
+
 (defn interpret-ast [ast ctx]
   (case (::ast/type ast)
 
@@ -306,6 +332,11 @@
 
     ::ast/ref (interpret-ref ast ctx)
 
+    ::ast/recur
+    {::data/recur true :tuple (interpret-ast (:tuple ast) ctx)}
+
+    ::ast/loop (interpret-loop ast ctx)
+
     ::ast/block
     (let [exprs (:exprs ast)
           inner (pop exprs)
@@ -366,15 +397,10 @@
       (println (ex-message e))
       (pp/pprint (ex-data e)))))
 
-(do
+(comment
 
   (def source "
 
-    ref foo = nil
-    ref bar = nil
-
-    eq (foo, bar)
-
     ")
 
   (println "")