From bea6ad2e5e7f102d42cf9cdea1a41e5e804fb763 Mon Sep 17 00:00:00 2001
From: Chris Pressey <cpressey@catseye.tc>
Date: Thu, 24 Feb 2022 20:50:40 +0000
Subject: [PATCH] Use new line number on error reporting to find a few type
 errors.

---
 HISTORY.md                                    |  2 +
 TODO.md                                       |  2 -
 eg/assoc2.castile                             | 37 +++++++++++++++++++
 eg/length.castile                             | 23 ------------
 ...kedlist.castile => linkedlist-ops.castile} |  8 ++++
 5 files changed, 47 insertions(+), 25 deletions(-)
 create mode 100644 eg/assoc2.castile
 delete mode 100644 eg/length.castile
 rename eg/{equal-linkedlist.castile => linkedlist-ops.castile} (80%)

diff --git a/HISTORY.md b/HISTORY.md
index c2fe48b..3cd5465 100644
--- a/HISTORY.md
+++ b/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.
diff --git a/TODO.md b/TODO.md
index 145365c..4a2ad53 100644
--- a/TODO.md
+++ b/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.
 
diff --git a/eg/assoc2.castile b/eg/assoc2.castile
new file mode 100644
index 0000000..c9952a8
--- /dev/null
+++ b/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");
+}
diff --git a/eg/length.castile b/eg/length.castile
deleted file mode 100644
index 6864ef0..0000000
--- a/eg/length.castile
+++ /dev/null
@@ -1,23 +0,0 @@
-struct list {
-  value: string;
-  next: list|void;
-} for (cons, singleton, length)
-
-fun cons(v: string, l: list) {
-  make list(value:v, next:l as list|void)
-}
-
-fun singleton(v: string) {
-  make list(value:v, next:null as list|void)
-}
-
-length : list|void -> integer
-fun length(l: list|void) {
-  typecase l is void { return 0 }
-  typecase l is list { return 1 + length(l.next) }
-}
-
-fun main() {
-  l = cons("first", cons("second", singleton("third")));
-  print(str(length(l as list|void)));
-}
diff --git a/eg/equal-linkedlist.castile b/eg/linkedlist-ops.castile
similarity index 80%
rename from eg/equal-linkedlist.castile
rename to eg/linkedlist-ops.castile
index 5475462..2b5a022 100644
--- a/eg/equal-linkedlist.castile
+++ b/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")
   }