From bf63701dfaa06f0f6d7d60111278fbce8e6d2ac1 Mon Sep 17 00:00:00 2001
From: Chris Pressey <cpressey@catseye.tc>
Date: Tue, 15 Feb 2022 12:00:21 +0000
Subject: [PATCH] Checkpoint.

---
 eg/length.castile   | 23 +++++++++++++++++++++++
 src/castile/main.py |  8 +++++++-
 tests/Castile.md    | 28 ++++++++++++++--------------
 3 files changed, 44 insertions(+), 15 deletions(-)
 create mode 100644 eg/length.castile

diff --git a/eg/length.castile b/eg/length.castile
new file mode 100644
index 0000000..1a1a02f
--- /dev/null
+++ b/eg/length.castile
@@ -0,0 +1,23 @@
+struct list {
+  value: string;
+  next: list|void;
+} for (cons, singleton, len)
+
+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/src/castile/main.py b/src/castile/main.py
index 3efd9cd..849c760 100644
--- a/src/castile/main.py
+++ b/src/castile/main.py
@@ -55,7 +55,13 @@ def main(argv):
         if options.typecheck:
             t = TypeChecker()
             t.collect_structs(ast)
-            t.type_of(ast)
+            try:
+                t.type_of(ast)
+            except Exception:
+                if options.show_ast:
+                    print(ast.pprint(0))
+                    print("-----")
+                raise
         if options.compile_to is not None:
             x = FunctionLifter()
             ast = x.lift_functions(ast)
diff --git a/tests/Castile.md b/tests/Castile.md
index 855f14b..428d856 100644
--- a/tests/Castile.md
+++ b/tests/Castile.md
@@ -1262,7 +1262,7 @@ is accomplished.
     | struct list {
     |   value: string;
     |   next: list|void;
-    | } for (cons, singleton, empty)
+    | } for (cons, singleton, len)
     | 
     | fun cons(v: string, l: list) {
     |   make list(value:v, next:l as list|void)
@@ -1272,22 +1272,22 @@ is accomplished.
     |   make list(value:v, next:null as list|void)
     | }
     | 
-    | fun empty(l: list|void) {
-    |   a = "no";
-    |   typecase l is void { a = "yes"; }
-    |   return a;
+    | len : 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(empty(l));
+    |   print(str(length(l as list|void)));
     | }
-    = no
+    = 3
 
     | struct list {
     |   value: string;
     |   next: list|void;
-    | } for (cons, singleton, empty)
+    | } for (cons, singleton, len)
     | 
     | fun cons(v: string, l: list) {
     |   make list(value:v, next:l as list|void)
@@ -1297,22 +1297,22 @@ is accomplished.
     |   make list(value:v, next:null as list|void)
     | }
     | 
-    | fun empty(l: list|void) {
-    |   a = "no";
-    |   typecase l is void { a = "yes"; }
-    |   return a;
+    | len : 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 = make list(value:"first", next:null);
-    |   print(empty(l));
+    |   print(str(length(l)));
     | }
     ? make
 
     | struct list {
     |   value: string;
     |   next: list|void;
-    | } for (cons, singleton, empty)
+    | } for (cons, singleton, len)
     | 
     | fun cons(v: string, l: list) {
     |   make list(value:v, next:l as list|void)