diff --git a/Makefile b/Makefile
index 2de36a55..858140c4 100644
--- a/Makefile
+++ b/Makefile
@@ -41,7 +41,7 @@ debug: $(GST_TARGET)
 	gdb $(GST_TARGET)
 
 valgrind: $(GST_TARGET)
-	valgrind ./$(GST_TARGET) --leak-check=full
+	valgrind ./$(GST_TARGET)
 
 clean:
 	rm $(GST_TARGET) || true
diff --git a/client/main.c b/client/main.c
index 1959a4e4..ab08e11e 100644
--- a/client/main.c
+++ b/client/main.c
@@ -6,64 +6,19 @@
 #include <gst/stl.h>
 #include <gst/disasm.h>
 
-/* Parse a file and execute it */
-int debug_run(Gst *vm, FILE *in) {
-    char buffer[1024] = {0};
-    const char *reader = buffer;
-    GstValue func;
-    GstParser p;
+/* Compile and run an ast */
+int debug_compile_and_run(Gst *vm, GstValue ast) {
     GstCompiler c;
-
-    gst_parser(&p, vm);
-
-    /* Create do struct */
-    GstArray *arr = gst_array(vm, 10);
-    gst_array_push(vm, arr, gst_string_cv(vm, "do"));
-
-    /* Get and parse input until we have a full form */
-    while (p.status != GST_PARSER_ERROR) {
-        if (*reader == '\0') {
-            if (!fgets(buffer, sizeof(buffer), in)) {
-                break;
-            }
-            reader = buffer;
-        }
-        reader += gst_parse_cstring(&p, reader);
-        if (gst_parse_hasvalue(&p))
-            gst_array_push(vm, arr, gst_parse_consume(&p));
-    }
-
-    /* Turn array into tuple */
-    GstValue *tup = gst_tuple_begin(vm, arr->count);
-    gst_memcpy(tup, arr->data, arr->count * sizeof(GstValue));
-    vm->ret.type = GST_TUPLE;
-    vm->ret.data.tuple = gst_tuple_end(vm, tup);
-
-    /* Check if file read in correctly */
-    if (p.error) {
-        printf("Parse error: %s\n", p.error);
-        return 1;
-    }
-
-    /* Check that parser is complete */
-    if (p.status != GST_PARSER_FULL && p.status != GST_PARSER_ROOT) {
-        printf("Unexpected end of source\n");
-        return 1;
-    }
-
+    GstValue func;
     /* Try to compile generated AST */
     gst_compiler(&c, vm);
-    func.type = GST_NIL;
     gst_compiler_usemodule(&c, "std");
-    func.type = GST_FUNCTION;
-    func.data.function = gst_compiler_compile(&c, vm->ret);
-
+    func = gst_wrap_function(gst_compiler_compile(&c, ast));
     /* Check for compilation errors */
     if (c.error) {
         printf("Compiler error: %s\n", c.error);
         return 1;
     }
-
     /* Execute function */
     if (gst_run(vm, func)) {
         if (vm->crash) {
@@ -76,23 +31,101 @@ int debug_run(Gst *vm, FILE *in) {
     return 0;
 }
 
-int main(int argc, const char **argv) {
+/* Parse a file and execute it */
+int debug_run(Gst *vm, FILE *in) {
+    char buffer[1024] = {0};
+    const char *reader = buffer;
+    GstValue ast;
+    GstValue *tup;
+    GstArray *arr;
+    GstParser p;
+    /* Init parser */
+    gst_parser(&p, vm);
+    /* Create do struct */
+    arr = gst_array(vm, 10);
+    gst_array_push(vm, arr, gst_string_cv(vm, "do"));
+    /* Get and parse input until we have a full form */
+    while (p.status != GST_PARSER_ERROR) {
+        if (*reader == '\0') {
+            if (!fgets(buffer, sizeof(buffer), in)) {
+                break;
+            }
+            reader = buffer;
+        }
+        reader += gst_parse_cstring(&p, reader);
+        if (gst_parse_hasvalue(&p))
+            gst_array_push(vm, arr, gst_parse_consume(&p));
+    }
+    /* Turn array into tuple */
+    tup = gst_tuple_begin(vm, arr->count);
+    gst_memcpy(tup, arr->data, arr->count * sizeof(GstValue));
+    ast = gst_wrap_tuple(gst_tuple_end(vm, tup));
+    /* Check if file read in correctly */
+    if (p.error) {
+        printf("Parse error: %s\n", p.error);
+        return 1;
+    }
+    /* Check that parser is complete */
+    if (p.status != GST_PARSER_FULL && p.status != GST_PARSER_ROOT) {
+        printf("Unexpected end of source\n");
+        return 1;
+    }
+    return debug_compile_and_run(vm, ast);
+}
 
+/* A simple repl */
+int debug_repl(Gst *vm) {
+    char buffer[10] = {0};
+    const char *reader = buffer;
+    GstParser p;
+    int reset;
+    for (;;) {
+        /* Init parser */
+        gst_parser(&p, vm);
+        reset = 1;
+        while (p.status != GST_PARSER_ERROR && p.status != GST_PARSER_FULL) {
+            if (*reader == '\0') {
+                if (reset)
+                    printf(">> ");
+                reset = 0;
+                if (!fgets(buffer, sizeof(buffer), stdin)) {
+                    break;
+                }
+                reader = buffer;
+            }
+            reader += gst_parse_cstring(&p, reader);
+        }
+        /* Check if file read in correctly */
+        if (p.error) {
+            printf("Parse error: %s\n", p.error);
+            continue;
+        }
+        /* Check that parser is complete */
+        if (p.status != GST_PARSER_FULL && p.status != GST_PARSER_ROOT) {
+            printf("Unexpected end of source\n");
+            continue;
+        }
+        if (0 == debug_compile_and_run(vm, gst_parse_consume(&p))) {
+            printf("%s\n", gst_to_string(vm, vm->ret));
+        }
+    }
+}
+
+int main(int argc, const char **argv) {
     Gst vm;
     int status = 0;
+
     gst_init(&vm);
     gst_stl_load(&vm);
-
-    const char *filename;
-
-   // if (argc > 1) {
-    //    filename = argv[1];
-    //} else {
-        filename = "libs/stl.gst";
-    //}
-
-    FILE *f = fopen(filename, "rb"); 
-    status = debug_run(&vm, f);
+    if (argc > 1) {
+        const char *filename;
+        FILE *f;
+        filename = argv[1];
+        f = fopen(filename, "rb"); 
+        status = debug_run(&vm, f);
+    } else {
+        status = debug_repl(&vm);
+    }
 
     gst_deinit(&vm);
 
diff --git a/core/parse.c b/core/parse.c
index 618037cc..97082548 100644
--- a/core/parse.c
+++ b/core/parse.c
@@ -422,7 +422,7 @@ static void dispatch_char(GstParser *p, uint8_t c) {
         }
     }
     /* Dispatch character to state */
-    while (!done && (p->status == GST_PARSER_PENDING || p->status == GST_PARSER_ROOT)) {
+    while (!done) {
         GstParseState *top = parser_peek(p);
         switch (top->type) {
             case PTYPE_ROOT:
diff --git a/core/stl.c b/core/stl.c
index 7c0e08f2..3447f4a7 100644
--- a/core/stl.c
+++ b/core/stl.c
@@ -391,6 +391,21 @@ int gst_stl_serialize(Gst *vm) {
 
 /* TODO - add userdata to allow for manipulation of FILE pointers. */
 
+int gst_stl_open(Gst *vm) {
+    GstValue ret;
+    const uint8_t *fname = gst_to_string(vm, gst_arg(vm, 0));
+    const uint8_t *fmode = gst_to_string(vm, gst_arg(vm, 1));
+    FILE *f;
+    if (gst_count_args(vm) < 2)
+        gst_c_throwc(vm, "expected filename and filemode");
+    f = fopen((const char *)fname, (const char *)fmode);
+    if (!f)
+        gst_c_throwc(vm, "could not open file");
+    ret.type = GST_USERDATA;
+    ret.data.pointer = f;
+    gst_c_return(vm, ret);
+}
+
 /****/
 /* Bootstraping */
 /****/
@@ -421,6 +436,7 @@ static const GstModuleItem const std_module[] = {
     {"rawset", gst_stl_rawset},
     {"error", gst_stl_error},
     {"serialize", gst_stl_serialize},
+    {"open", gst_stl_open},
     {NULL, NULL}
 };
 
diff --git a/libs/stl.gst b/libs/stl.gst
index 26ddb05b..4180ef7d 100644
--- a/libs/stl.gst
+++ b/libs/stl.gst
@@ -1,2 +1,4 @@
 (print 1)
 
+(: counter 0)
+(while (< counter 100) (print counter) (: counter (+ 1 counter)))