From 90f3229af595dc7acd596aec405037e74d5247f6 Mon Sep 17 00:00:00 2001
From: Steve Dunham <dunhamsteve@gmail.com>
Date: Wed, 11 Sep 2024 16:23:14 -0700
Subject: [PATCH] Don't run switch for single cases

---
 TODO.md             |  5 +++--
 src/Lib/Compile.idr | 14 ++++++++------
 2 files changed, 11 insertions(+), 8 deletions(-)

diff --git a/TODO.md b/TODO.md
index d0a6d67..4d88831 100644
--- a/TODO.md
+++ b/TODO.md
@@ -8,6 +8,7 @@
 - [ ] operators
 - [ ] import
 - [ ] add {{ }} and solving autos
+- [ ] do blocks
 - [ ] some solution for + (classes? ambiguity?)
 - [ ] show compiler failure in the editor (exit code != 0)
 - [ ] write js files into `out` directory
@@ -17,8 +18,8 @@
 - [ ] type at point in vscode
 - [ ] repl
 - [ ] LSP
-- [ ] don't match forced constructors at runtime
-  - maybe do this in codegen if there is only one case.
+- [x] don't match forced constructors at runtime
+  - I think we got this by not switching for single cases
 - [ ] magic nat (codegen as number with appropriate pattern matching)
 - [ ] magic tuple? (codegen as array)
 - [ ] magic newtype? (drop in codegen)
diff --git a/src/Lib/Compile.idr b/src/Lib/Compile.idr
index 594f417..d09fafe 100644
--- a/src/Lib/Compile.idr
+++ b/src/Lib/Compile.idr
@@ -119,19 +119,21 @@ termToJS env (CCase t alts) f =
   -- TODO default case, let's drop the extra field.
 
   termToJS env t $ \case
-    (Var nm) => (JCase (Dot (Var nm) "tag") (map (termToJSAlt nm) alts))
+    (Var nm) => maybeCaseStmt nm alts
     t' =>
       let nm = fresh "sc" env in
-        JSnoc (JConst nm t')
-          (JCase (Dot (Var nm) "tag") (map (termToJSAlt nm) alts))
+        JSnoc (JConst nm t') (maybeCaseStmt nm alts)
+
   where
     termToJSAlt : String -> CAlt -> JAlt
     termToJSAlt nm (CConAlt name args u) = JConAlt name (termToJS (mkEnv nm 0 env args) u f)
     -- intentionally reusing scrutinee name here
     termToJSAlt nm (CDefAlt u) = JDefAlt (termToJS (Var nm :: env) u f)
-    label : JSExp -> (String -> JSStmt e) -> JSStmt e
-    label (Var nm) f = f nm
-    label t f = ?label_rhs
+
+    maybeCaseStmt : String -> List CAlt -> JSStmt e
+    -- If there is a single alt, assume it matched
+    maybeCaseStmt nm [(CConAlt _ args u)] = (termToJS (mkEnv nm 0 env args) u f)
+    maybeCaseStmt nm alts = (JCase (Dot (Var nm) "tag") (map (termToJSAlt nm) alts))
 
 
 -- FIXME escape