Add REPL

Makefile

@@ -16,6 +16,9 @@ OBJS = \
 run: lisp
 	./lisp
 
+repl: lisp
+	./lisp --repl
+
 test: lisp
 	./lisp --test
 

src/main.c

@@ -13,6 +13,7 @@
 #include <string.h>
 
 static void run();
+static void repl();
 static void test();
 
 int main(int argc, char **argv)
@@ -23,6 +24,8 @@ int main(int argc, char **argv)
         run();
     } else if (argc == 2 && strcmp(argv[1], "--test") == 0) {
         test();
+    } else if (argc == 2 && strcmp(argv[1], "--repl") == 0) {
+        repl();
     } else {
         abort();
     }
@@ -116,8 +119,10 @@ struct Object *eval_list(struct Object *const object)
 void run()
 {
     Tokens tokens = Tokens_new();
-    Lexer lexer = Lexer_new(tokens);
     assert(tokens);
+
+    Lexer lexer = Lexer_new(tokens);
+    assert(lexer);
     char chr;
     while ((chr = getchar()) != EOF) {
         Lexer_lex(lexer, chr);
@@ -146,6 +151,42 @@ void run()
     Object_print(result, 0);
 }
 
+void repl()
+{
+    while (true) {
+        Tokens tokens = Tokens_new();
+        assert(tokens);
+
+        Lexer lexer = Lexer_new(tokens);
+        assert(lexer);
+
+        printf("> ");
+        while (true) {
+            const char chr = getchar();
+            if (chr == EOF) {
+                putchar('\n');
+                exit(EXIT_SUCCESS);
+            }
+
+            if (chr == '\n') {
+                Lexer_lex(lexer, '\n');
+                break;
+            }
+
+            Lexer_lex(lexer, chr);
+        }
+
+        LEXER_DELETE(lexer);
+
+        struct Object *const program = parse(tokens);
+        TOKENS_DELETE(tokens);
+
+        struct Object *const result = eval(program);
+
+        eval(Object_build_list(2, Object_new_symbol("displayln"), result));
+    }
+}
+
 // Macros
 static void test_if();
 // Basic data structures