Current state of mal for Clojure West lighting talk.

1 files changed, 61 insertions, 0 deletions

diff --git a/clojure/src/step2_eval.clj b/clojure/src/step2_eval.clj
new file mode 100644
index 0000000..6ff9eb3
--- /dev/null
+++ b/clojure/src/step2_eval.clj
@@ -0,0 +1,61 @@
+(ns step2-eval
+    (:require [clojure.repl]
+              [types]
+              [readline]
+              [reader]))
+
+(declare EVAL)
+
+;; read
+(defn READ [& [strng]]
+  (let [line (if strng strng (read-line))]
+    (reader/read-string strng)))
+
+;; eval
+(defn eval-ast [ast env]
+  (cond
+    (symbol? ast) (or (get env ast)
+                      (throw (Error. (str ast " not found"))))
+   
+    (seq? ast)    (doall (map #(EVAL % env) ast))
+
+    (vector? ast) (vec (doall (map #(EVAL % env) ast)))
+   
+    (map? ast)    (apply hash-map (doall (map #(EVAL % env)
+                                              (mapcat identity ast))))
+
+    :else         ast))
+
+(defn EVAL [ast env]
+  ;;(prn "EVAL" ast (keys @env)) (flush)
+  (if (not (seq? ast))
+    (eval-ast ast env)
+
+    ;; apply list
+    (let [el (eval-ast ast env)
+          f (first el)
+          args (rest el)]
+      (apply f args))))
+
+;; print
+(defn PRINT [exp] (pr-str exp))
+
+;; repl
+(def repl-env {'+ +
+               '- -
+               '* *
+               '/ /})
+(defn rep
+  [strng]
+  (PRINT (EVAL (READ strng), repl-env)))
+
+(defn -main [& args]
+  (loop []
+    (let [line (readline/readline "user> ")]
+      (when line
+        (when-not (re-seq #"^\s*$|^\s*;.*$" line) ; blank/comment
+          (try
+            (println (rep line))
+            (catch Throwable e
+              (clojure.repl/pst e))))
+        (recur)))))