Use new line number on error reporting to find a few type errors.

HISTORY.md

@@ -22,6 +22,8 @@ Castile 0.5
 
 ### Implementation
 
+*   Line numbers are recorded in the AST when parsing, and
+    reported on type errors when type errors occur.
 *   Requesting the AST be dumped, will also dump the AST with
     type assignments, if an error occurs during type checking.
 *   Established an abstract base class for compiler backends.

TODO.md

@@ -19,8 +19,6 @@ stackmac: store tagged values as two values on the stack.
 and void types in unions of (void, X) should only be one value.
 (structs are still boxed though)
 
-AST nodes should have source line numbers, it would be really nice.
-
 Implement garbage collection of some sort in the C backend.  Either that
 or implement some kind of resource-awareness in the language itself.
 

eg/assoc2.castile

@@ -0,0 +1,37 @@
+struct assoc {
+  key: string;
+  value: string;
+  next: assoc|void;
+} for (update, lookup, remove)
+
+fun empty() {
+  return null as assoc|void
+}
+
+fun update(k: string, v: string, a: assoc|void) {
+  make assoc(key:k, value:v, next:a as assoc|void)
+}
+
+lookup : assoc|void, string -> string|void
+fun lookup(a: assoc|void, k: string) {
+  typecase a is void {
+    return null as string|void
+  }
+  typecase a is assoc {
+    if a.key == k {
+      return a.value as string|void
+    }
+    return lookup(a.next, k)
+  }
+}
+
+fun main() {
+  a = update("3", "third", empty());
+  a = update("2", "second", a as assoc|void);
+  a = update("1", "first", a as assoc|void);
+  r = lookup((a as assoc|void), "2");
+  print("um");
+  typecase r is void { print("NOT FOUND"); }
+  typecase r is string { print(r); }
+  print("ya");
+}

eg/equal-linkedlist.castile → eg/linkedlist-ops.castile

@@ -26,11 +26,19 @@ fun equal_list(a: list|void, b: list|void) {
   return false
 }
 
+length : list|void -> integer
+fun length(l: list|void) {
+  typecase l is void { return 0 }
+  typecase l is list { return 1 + length(l.next) }
+}
+
 main = fun() {
   l1 = cons("first", cons("second", cons("third", empty())));
   l2 = cons("first", cons("second", cons("third", empty())));
   l3 = cons("first", cons("second", empty()));
 
+  print(str(length(l1 as list|void)));
+
   if (equal_list(l1, l2) and not equal_list(l2, l3)) {
     print("Yep, story checks out")
   }