From 448e805293989b06e07878a4a87fdd378f7c6e02 Mon Sep 17 00:00:00 2001
From: Bruce Hill <bruce@bruce-hill.com>
Date: Sun, 6 Apr 2025 15:09:44 -0400
Subject: Re-implement multiple patterns for `when` blocks

---
 src/parse.c   | 14 ++++++++++----
 test/enums.tm | 12 ++++++++++++
 test/when.tm  | 19 ++++++++++++-------
 3 files changed, 34 insertions(+), 11 deletions(-)

diff --git a/src/parse.c b/src/parse.c
index a11fc971..0f76243d 100644
--- a/src/parse.c
+++ b/src/parse.c
@@ -996,11 +996,17 @@ PARSER(parse_when) {
         spaces(&pos);
         ast_t *pattern = expect(ctx, start, &pos, parse_expr, "I expected a pattern to match here");
         spaces(&pos);
-        tmp = pos;
-        if (!match(&tmp, ":"))
-            parser_err(ctx, tmp, tmp, "I expected a colon ':' after this clause");
+        when_clause_t *new_clauses = new(when_clause_t, .pattern=pattern, .next=clauses);
+        while (match(&pos, ",")) {
+            pattern = expect(ctx, start, &pos, parse_expr, "I expected a pattern to match here");
+            new_clauses = new(when_clause_t, .pattern=pattern, .next=new_clauses);
+            spaces(&pos);
+        }
         ast_t *body = expect(ctx, start, &pos, parse_block, "I expected a body for this 'when' clause"); 
-        clauses = new(when_clause_t, .pattern=pattern, .body=body, .next=clauses);
+        for (when_clause_t *c = new_clauses; c && c != clauses; c = c->next) {
+            c->body = body;
+        }
+        clauses = new_clauses;
         tmp = pos;
         whitespace(&tmp);
     }
diff --git a/test/enums.tm b/test/enums.tm
index 19590353..a11f95f9 100644
--- a/test/enums.tm
+++ b/test/enums.tm
@@ -66,6 +66,18 @@ func main():
 	while when cases[i] is One(x):
 		>> x
 		i += 1
+
+	>> [
+		(
+			when x is One(y), Two(y,_):
+				"Small $y"
+			is Zero:
+				"Zero"
+			else:
+				"Other"
+		) for x in [Foo.Zero, Foo.One(1), Foo.Two(2,2), Foo.Three(3,"",no)]
+	]
+	= ["Zero", "Small 1", "Small 2", "Other"]
 	
 	>> expr := when cases[1] is One(y):
 		y + 1
diff --git a/test/when.tm b/test/when.tm
index 77c97af5..d93745dd 100644
--- a/test/when.tm
+++ b/test/when.tm
@@ -1,13 +1,18 @@
 # Tests for the 'when' block
 
 func main():
-    str := "B"
-    when str is "A":
-        fail("First")
-    is "B":
-        say("Success")
-    is "C":
-        fail("Third")
+    answers := [
+        (
+            when x is "A","B":
+                "A or B"
+            is "C":
+                "C"
+            else:
+                "Other"
+        ) for x in ["A", "B", "C", "D"]
+    ]
+    >> answers
+    = ["A or B", "A or B", "C", "Other"]
 
     n := 23
     >> when n is 1: Int64(1)
-- 
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