Interpret refs

src/ludus/interpreter.clj

@@ -267,6 +267,16 @@
         result ;; TODO: test this!
         ))))
 
+(defn- interpret-ref [ast ctx]
+  (let [name (:name ast) expr (:expr ast)]
+    (if (contains? @ctx name)
+      (throw (ex-info (str "Name " name " is already bound") {})))
+    (let [value (interpret-ast expr ctx)
+          box (atom value)
+          ref {::data/ref true ::data/value box ::data/name name}]
+      (vswap! ctx update-ctx {name ref})
+      ref)))
+
 (defn interpret-ast [ast ctx]
   (case (::ast/type ast)
 
@@ -294,6 +304,8 @@
 
     ::ast/import (interpret-import ast ctx)
 
+    ::ast/ref (interpret-ref ast ctx)
+
     ::ast/block
     (let [exprs (:exprs ast)
           inner (pop exprs)
@@ -346,23 +358,28 @@
       (pp/pprint (ex-data e))
       (System/exit 67))))
 
-(comment
+(defn interpret-safe [parsed]
+  (try 
+    (interpret-ast (::parser/ast parsed) {})
+    (catch clojure.lang.ExceptionInfo e
+      (println "Ludus panicked!")
+      (println (ex-message e))
+      (pp/pprint (ex-data e)))))
+
+(do
 
   (def source "
 
-    let foo = 2
+    fn swap! (r, f) -> {
-
+      let val = deref (r)
-    match foo with {
+      let new = f (val)
-      1 -> :one
+      set! (r, new)
-      2 -> :two
-      else -> :oops
     }
 
-    ns bar {
+    ref foo = 0
-      foo
-    }
 
-    bar :foo
+    swap! (foo, inc)
+    swap! (foo, inc)
 
     ")
 
@@ -374,7 +391,7 @@
   (-> source
     (scanner/scan)
     (parser/parse)
-    (interpret)
+    (interpret-safe)
     (pp/pprint)))
 
 (comment "