diff --git a/edify/main.c b/edify/main.c
index 7da89e2..03eefc6 100644
--- a/edify/main.c
+++ b/edify/main.c
@@ -21,152 +21,183 @@
 #include "expr.h"
 #include "parser.h"
 
+extern int yyparse(Expr** root, int* error_count);
+
 int expect(const char* expr_str, const char* expected, int* errors) {
-  Expr* e;
-  int error;
-  char* result;
+    Expr* e;
+    int error;
+    char* result;
 
-  printf(".");
+    printf(".");
 
-  yy_scan_string(expr_str);
-  error = yyparse(&e);
-  if (error > 0) {
-    fprintf(stderr, "error parsing \"%s\"\n", expr_str);
-    ++*errors;
-    return 0;
-  }
+    yy_scan_string(expr_str);
+    int error_count = 0;
+    error = yyparse(&e, &error_count);
+    if (error > 0 || error_count > 0) {
+        fprintf(stderr, "error parsing \"%s\" (%d errors)\n",
+                expr_str, error_count);
+        ++*errors;
+        return 0;
+    }
 
-  result = Evaluate(NULL, e);
-  if (result == NULL && expected != NULL) {
-    fprintf(stderr, "error evaluating \"%s\"\n", expr_str);
-    ++*errors;
-    return 0;
-  }
+    State state;
+    state.cookie = NULL;
+    state.script = expr_str;
+    state.errmsg = NULL;
 
-  if (result == NULL && expected == NULL) {
-    return 1;
-  }
+    result = Evaluate(&state, e);
+    free(state.errmsg);
+    if (result == NULL && expected != NULL) {
+        fprintf(stderr, "error evaluating \"%s\"\n", expr_str);
+        ++*errors;
+        return 0;
+    }
 
-  if (strcmp(result, expected) != 0) {
-    fprintf(stderr, "evaluating \"%s\": expected \"%s\", got \"%s\"\n",
-            expr_str, expected, result);
-    ++*errors;
+    if (result == NULL && expected == NULL) {
+        return 1;
+    }
+
+    if (strcmp(result, expected) != 0) {
+        fprintf(stderr, "evaluating \"%s\": expected \"%s\", got \"%s\"\n",
+                expr_str, expected, result);
+        ++*errors;
+        free(result);
+        return 0;
+    }
+
     free(result);
-    return 0;
-  }
-
-  free(result);
-  return 1;
+    return 1;
 }
 
 int test() {
-  int errors = 0;
+    int errors = 0;
 
-  expect("a", "a", &errors);
-  expect("\"a\"", "a", &errors);
-  expect("\"\\x61\"", "a", &errors);
-  expect("# this is a comment\n"
-         "  a\n"
-         "   \n",
-         "a", &errors);
+    expect("a", "a", &errors);
+    expect("\"a\"", "a", &errors);
+    expect("\"\\x61\"", "a", &errors);
+    expect("# this is a comment\n"
+           "  a\n"
+           "   \n",
+           "a", &errors);
 
 
-  // sequence operator
-  expect("a; b; c", "c", &errors);
+    // sequence operator
+    expect("a; b; c", "c", &errors);
 
-  // string concat operator
-  expect("a + b", "ab", &errors);
-  expect("a + \n \"b\"", "ab", &errors);
-  expect("a + b +\nc\n", "abc", &errors);
+    // string concat operator
+    expect("a + b", "ab", &errors);
+    expect("a + \n \"b\"", "ab", &errors);
+    expect("a + b +\nc\n", "abc", &errors);
 
-  // string concat function
-  expect("concat(a, b)", "ab", &errors);
-  expect("concat(a,\n \"b\")", "ab", &errors);
-  expect("concat(a + b,\nc,\"d\")", "abcd", &errors);
-  expect("\"concat\"(a + b,\nc,\"d\")", "abcd", &errors);
+    // string concat function
+    expect("concat(a, b)", "ab", &errors);
+    expect("concat(a,\n \"b\")", "ab", &errors);
+    expect("concat(a + b,\nc,\"d\")", "abcd", &errors);
+    expect("\"concat\"(a + b,\nc,\"d\")", "abcd", &errors);
 
-  // logical and
-  expect("a && b", "b", &errors);
-  expect("a && \"\"", "", &errors);
-  expect("\"\" && b", "", &errors);
-  expect("\"\" && \"\"", "", &errors);
-  expect("\"\" && abort()", "", &errors);   // test short-circuiting
-  expect("t && abort()", NULL, &errors);
+    // logical and
+    expect("a && b", "b", &errors);
+    expect("a && \"\"", "", &errors);
+    expect("\"\" && b", "", &errors);
+    expect("\"\" && \"\"", "", &errors);
+    expect("\"\" && abort()", "", &errors);   // test short-circuiting
+    expect("t && abort()", NULL, &errors);
 
-  // logical or
-  expect("a || b", "a", &errors);
-  expect("a || \"\"", "a", &errors);
-  expect("\"\" || b", "b", &errors);
-  expect("\"\" || \"\"", "", &errors);
-  expect("a || abort()", "a", &errors);     // test short-circuiting
-  expect("\"\" || abort()", NULL, &errors);
+    // logical or
+    expect("a || b", "a", &errors);
+    expect("a || \"\"", "a", &errors);
+    expect("\"\" || b", "b", &errors);
+    expect("\"\" || \"\"", "", &errors);
+    expect("a || abort()", "a", &errors);     // test short-circuiting
+    expect("\"\" || abort()", NULL, &errors);
 
-  // logical not
-  expect("!a", "", &errors);
-  expect("! \"\"", "t", &errors);
-  expect("!!a", "t", &errors);
+    // logical not
+    expect("!a", "", &errors);
+    expect("! \"\"", "t", &errors);
+    expect("!!a", "t", &errors);
 
-  // precedence
-  expect("\"\" == \"\" && b", "b", &errors);
-  expect("a + b == ab", "t", &errors);
-  expect("ab == a + b", "t", &errors);
-  expect("a + (b == ab)", "a", &errors);
-  expect("(ab == a) + b", "b", &errors);
+    // precedence
+    expect("\"\" == \"\" && b", "b", &errors);
+    expect("a + b == ab", "t", &errors);
+    expect("ab == a + b", "t", &errors);
+    expect("a + (b == ab)", "a", &errors);
+    expect("(ab == a) + b", "b", &errors);
 
-  // substring function
-  expect("is_substring(cad, abracadabra)", "t", &errors);
-  expect("is_substring(abrac, abracadabra)", "t", &errors);
-  expect("is_substring(dabra, abracadabra)", "t", &errors);
-  expect("is_substring(cad, abracxadabra)", "", &errors);
-  expect("is_substring(abrac, axbracadabra)", "", &errors);
-  expect("is_substring(dabra, abracadabrxa)", "", &errors);
+    // substring function
+    expect("is_substring(cad, abracadabra)", "t", &errors);
+    expect("is_substring(abrac, abracadabra)", "t", &errors);
+    expect("is_substring(dabra, abracadabra)", "t", &errors);
+    expect("is_substring(cad, abracxadabra)", "", &errors);
+    expect("is_substring(abrac, axbracadabra)", "", &errors);
+    expect("is_substring(dabra, abracadabrxa)", "", &errors);
 
-  // ifelse function
-  expect("ifelse(t, yes, no)", "yes", &errors);
-  expect("ifelse(!t, yes, no)", "no", &errors);
-  expect("ifelse(t, yes, abort())", "yes", &errors);
-  expect("ifelse(!t, abort(), no)", "no", &errors);
+    // ifelse function
+    expect("ifelse(t, yes, no)", "yes", &errors);
+    expect("ifelse(!t, yes, no)", "no", &errors);
+    expect("ifelse(t, yes, abort())", "yes", &errors);
+    expect("ifelse(!t, abort(), no)", "no", &errors);
 
-  // if "statements"
-  expect("if t then yes else no endif", "yes", &errors);
-  expect("if \"\" then yes else no endif", "no", &errors);
-  expect("if \"\" then yes endif", "", &errors);
-  expect("if \"\"; t then yes endif", "yes", &errors);
+    // if "statements"
+    expect("if t then yes else no endif", "yes", &errors);
+    expect("if \"\" then yes else no endif", "no", &errors);
+    expect("if \"\" then yes endif", "", &errors);
+    expect("if \"\"; t then yes endif", "yes", &errors);
 
-  printf("\n");
+    printf("\n");
 
-  return errors;
+    return errors;
+}
+
+void ExprDump(int depth, Expr* n, char* script) {
+    printf("%*s", depth*2, "");
+    char temp = script[n->end];
+    script[n->end] = '\0';
+    printf("%s %p (%d-%d) \"%s\"\n",
+           n->name == NULL ? "(NULL)" : n->name, n->fn, n->start, n->end,
+           script+n->start);
+    script[n->end] = temp;
+    int i;
+    for (i = 0; i < n->argc; ++i) {
+        ExprDump(depth+1, n->argv[i], script);
+    }
 }
 
 int main(int argc, char** argv) {
-  RegisterBuiltins();
-  FinishRegistration();
+    RegisterBuiltins();
+    FinishRegistration();
 
-  if (argc == 1) {
-    return test() != 0;
-  }
-
-  FILE* f = fopen(argv[1], "r");
-  char buffer[8192];
-  int size = fread(buffer, 1, 8191, f);
-  fclose(f);
-  buffer[size] = '\0';
-
-  Expr* root;
-  int error_count = 0;
-  yy_scan_bytes(buffer, size);
-  int error = yyparse(&root, &error_count);
-  printf("parse returned %d; %d errors encountered\n", error, error_count);
-  if (error == 0 || error_count > 0) {
-    char* result = Evaluate(NULL, root);
-    if (result == NULL) {
-      char* errmsg = GetError();
-      printf("result was NULL, message is: %s\n",
-             (errmsg == NULL ? "(NULL)" : errmsg));
-      ClearError();
-    } else {
-      printf("result is [%s]\n", result);
+    if (argc == 1) {
+        return test() != 0;
     }
-  }
-  return 0;
+
+    FILE* f = fopen(argv[1], "r");
+    char buffer[8192];
+    int size = fread(buffer, 1, 8191, f);
+    fclose(f);
+    buffer[size] = '\0';
+
+    Expr* root;
+    int error_count = 0;
+    yy_scan_bytes(buffer, size);
+    int error = yyparse(&root, &error_count);
+    printf("parse returned %d; %d errors encountered\n", error, error_count);
+    if (error == 0 || error_count > 0) {
+
+        ExprDump(0, root, buffer);
+
+        State state;
+        state.cookie = NULL;
+        state.script = buffer;
+        state.errmsg = NULL;
+
+        char* result = Evaluate(&state, root);
+        if (result == NULL) {
+            printf("result was NULL, message is: %s\n",
+                   (state.errmsg == NULL ? "(NULL)" : state.errmsg));
+            free(state.errmsg);
+        } else {
+            printf("result is [%s]\n", result);
+        }
+    }
+    return 0;
 }