All: split types into types, env, printer, core.

- types: low-level mapping to the implementation language.
- core: functions on types that are exposed directly to mal.
- printer: implementation called by pr-str, str, prn, println.
- env: the environment implementation

- Also, unindent all TCO while loops so that the diff of step4 and
  step5 are minimized.

1 files changed, 35 insertions, 0 deletions

diff --git a/clojure/src/env.clj b/clojure/src/env.clj
new file mode 100644
index 0000000..7f1f934
--- /dev/null
+++ b/clojure/src/env.clj
@@ -0,0 +1,35 @@
+(ns env)
+
+(defn env [& [outer binds exprs]]
+  ;;(prn "env" binds exprs)
+  ;; (when (not= (count binds) (count exprs))
+  ;;  (throw (Exception. "Arity mistmatch in env call")))
+  (atom
+    (loop [env {:outer outer}
+           b binds
+           e exprs]
+      (cond
+        (= nil b)
+        env
+        
+        (= '& (first b))
+        (assoc env (nth b 1) e)
+  
+        :else
+        (recur (assoc env (first b) (first e)) (next b) (next e))))))
+
+(defn env-find [env k]
+  (cond
+    (contains? @env k) env
+    (:outer @env) (env-find (:outer @env) k)
+    :else nil))
+
+(defn env-get [env k]
+  (let [e (env-find env k)]
+    (when-not e
+      (throw (Exception. (str "'" k "' not found"))))
+    (get @e k)))
+
+(defn env-set [env k v]
+  (swap! env assoc k v)
+  v)