Wire up CLI.

foo.ld

@@ -0,0 +1 @@
+print ("foo, bar, and baz")

src/ludus/core.clj

@@ -1,33 +1,33 @@
 (ns ludus.core
   "A tree-walk interpreter for the Ludus language."
   (:require
-   [ludus.scanner :as scanner]))
+    [ludus.scanner :as scanner]
-
+    [ludus.parser :as parser]
-(defn- report [line, where, message]
+    [ludus.interpreter :as interpreter]
-  (println (str "[line " line "] Error" where ": " message)))
+    [clojure.pprint :as pp]))
-
-(defn- error [line, message]
-  (report line "" message))
 
 (defn- run [source]
-  (let [tokens (scanner/scan source)]
+  (let [scanned (scanner/scan source)]
-    (run! println tokens)))
+    (if (not-empty (:errors scanned))
-
+      (do
-(defn- run-file [path]
+        (println "I found some scanning errors!")
-  (let [source (slurp path)]
+        (pp/pprint (:errors scanned))
-    (run source)))
+        (System/exit 65))
-
+      (let [parsed (parser/parse scanned)]
-(defn- run-prompt []
+        (if (not-empty (:errors parsed))
-  (loop [_ ""]
+          (do
-    (print "Ludus >> ")
+            (println "I found some parsing errors!")
-    (flush)
+            (pp/pprint (:errors parsed))
-    (when-let [line (read-line)]
+            (System/exit 66))
-      (recur (run line)))))
+          (let [interpreted (interpreter/interpret parsed)]
+            (println "   *** *** ***")
+            (println "I ran your script; here's the output: ")
+            (pp/pprint interpreted)
+            (System/exit 0)))))))
 
 (defn -main [& args]
   (cond
-    (> (count args) 1) (do
+    (= (count args) 1) (run (slurp (first args)))
+    :else (do
             (println "Usage: ludus [script]")
-                         (System/exit 64))
+            (System/exit 64))))
-    (= (count args) 1) (run-file (first args))
-    :else (run-prompt)))

src/ludus/interpreter.clj

@@ -19,7 +19,7 @@
         (recur word (::parent ctx))
         (throw (ex-info (str "Unbound name: " word) {}))))))
 
-(declare interpret match)
+(declare interpret-ast match)
 
 (defn- match-tuple [pattern value ctx-atom]
   (cond
@@ -72,7 +72,7 @@
 (defn- interpret-let [ast ctx]
   (let [pattern (:pattern ast)
         expr (:expr ast)
-        value (interpret expr ctx)
+        value (interpret-ast expr ctx)
         match (match pattern value ctx)
         success (:success match)]
     (if success
@@ -84,14 +84,14 @@
   (let [if-expr (:if ast)
         then-expr (:then ast)
         else-expr (:else ast)
-        if-value (interpret if-expr ctx)]
+        if-value (interpret-ast if-expr ctx)]
     (if if-value
-      (interpret then-expr ctx)
+      (interpret-ast then-expr ctx)
-      (interpret else-expr ctx))))
+      (interpret-ast else-expr ctx))))
 
 (defn- interpret-match [ast ctx]
   (let [match-expr (:expr ast)
-        expr (interpret match-expr ctx)
+        expr (interpret-ast match-expr ctx)
         clauses (:clauses ast)]
     (loop [clause (first clauses)
            clauses (rest clauses)]
@@ -105,7 +105,7 @@
           (if success
             (do
               (swap! new-ctx #(merge % clause-ctx))
-              (interpret body new-ctx))
+              (interpret-ast body new-ctx))
             (recur (first clauses) (rest clauses))))
         (throw (ex-info "Match Error: No match found" {}))))))
 
@@ -113,8 +113,8 @@
   ;; TODO: check this statically
   (if (not (= 1 (:length tuple)))
     (throw (ex-info "Called keywords must be unary" {}))
-    (let [kw (interpret kw ctx)
+    (let [kw (interpret-ast kw ctx)
-          map (second (interpret tuple ctx))]
+          map (second (interpret-ast tuple ctx))]
       (if (::data/struct map)
         (if (contains? map kw)
           (kw map)
@@ -123,7 +123,7 @@
       )))
 
 (defn- call-fn [fn tuple ctx]
-  (let [passed (interpret tuple ctx)]
+  (let [passed (interpret-ast tuple ctx)]
     (case (::data/type fn)
       ::data/clj (apply (:body fn) (next passed))
 
@@ -141,7 +141,7 @@
               (if success
                 (do
                   (swap! new-ctx #(merge % clause-ctx))
-                  (interpret body new-ctx))
+                  (interpret-ast body new-ctx))
                 (recur (first clauses) (rest clauses))))
 
             (throw (ex-info "Match Error: No match found" {:fn-name (:name fn)})))))
@@ -166,7 +166,8 @@
       (if (::data/struct prev-value)
         (if (contains? prev-value (:value curr))
           (get prev-value (:value curr))
-          (throw (ex-info (str "Struct error: no member " (:value curr)) {}))))
+          (throw (ex-info (str "Struct error: no member " (:value curr)) {})))
+        (get prev-value (:value curr)))
       (call-fn prev-value curr ctx))))
 
 (defn- interpret-synthetic [ast ctx]
@@ -177,7 +178,7 @@
         first-term-type (::ast/type first)
         first-val (if (= first-term-type ::ast/atom)
                     (interpret-called-kw first second ctx)
-                    (interpret-synthetic-term (interpret first ctx) second ctx))]
+                    (interpret-synthetic-term (interpret-ast first ctx) second ctx))]
     (reduce #(interpret-synthetic-term %1 %2 ctx) first-val rest)))
 
 (defn- interpret-fn [ast ctx]
@@ -201,7 +202,7 @@
          (let [[k v] kv]
            [k (f v)]))))
 
-(defn interpret [ast ctx]
+(defn interpret-ast [ast ctx]
   (case (::ast/type ast)
 
     ::ast/atom (:value ast)
@@ -223,43 +224,46 @@
           inner (pop exprs)
           last (peek exprs)
           ctx (atom {::parent ctx})]
-      (run! #(interpret % ctx) inner)
+      (run! #(interpret-ast % ctx) inner)
-      (interpret last ctx))
+      (interpret-ast last ctx))
 
     ::ast/script
     (let [exprs (:exprs ast)
           inner (pop exprs)
           last (peek exprs)
           ctx (atom prelude/prelude)]
-      (run! #(interpret % ctx) inner)
+      (run! #(interpret-ast % ctx) inner)
-      (interpret last ctx))
+      (interpret-ast last ctx))
 
     ;; note that, excepting tuples and structs,
     ;; runtime representations are bare
     ;; tuples are vectors with a special first member
     ::ast/tuple
     (let [members (:members ast)]
-      (into [::data/tuple] (map #(interpret % ctx)) members))
+      (into [::data/tuple] (map #(interpret-ast % ctx)) members))
 
     ::ast/list
     (let [members (:members ast)]
-      (into [] (map #(interpret % ctx)) members))
+      (into [] (map #(interpret-ast % ctx)) members))
 
     ::ast/set
     (let [members (:members ast)]
-      (into #{} (map #(interpret % ctx)) members))
+      (into #{} (map #(interpret-ast % ctx)) members))
 
     ::ast/hash
     (let [members (:members ast)]
-      (into {} (map-values #(interpret % ctx)) members))
+      (into {} (map-values #(interpret-ast % ctx)) members))
 
     ::ast/struct
     (let [members (:members ast)]
-      (into {::data/struct true} (map-values #(interpret % ctx)) members))
+      (into {::data/struct true} (map-values #(interpret-ast % ctx)) members))
 
     (throw (ex-info "Unknown AST node type" {:node ast}))))
 
-(do
+(defn interpret [parsed]
+  (interpret-ast (::parser/ast parsed) {}))
+
+(comment
 
   (def source "
 
@@ -267,6 +271,11 @@
 
     call (:foo, #{:foo 23})
 
+    let my_map = #{:foo 42, :bar 23, :baz \"frobulate\"}
+
+    my_map :foo
+
+
 	")
 
   (println "")
@@ -277,8 +286,7 @@
   (-> source
     (scanner/scan)
     (parser/parse)
-    (::parser/ast)
+    (interpret)
-    (interpret {})
     (pp/pprint)))
 
 (comment "

src/ludus/parser.clj

@@ -604,7 +604,7 @@
       (parser)
       (parse-script)))
 
-(do
+(comment
   (def pp pp/pprint)
   (def source "
 

src/ludus/scanner.clj

@@ -312,7 +312,7 @@
          :errors (::errors scanner)})
       (recur (-> scanner (scan-token) (next-token))))))
 
-(do
+(comment
   (def source "@{")
 
   (pp/pprint (scan source)))