fix idiom brackets to account for IAlternative

Things like (,) () aren't straightforward IVar's but are IAlternative's
which present options about how the term should resolve. [| |] was not
accounting for this.

src/Idris/Desugar.idr

@@ -114,6 +114,8 @@ bindBangs ((n, fc, btm) :: bs) tm
                                 (Implicit fc False) tm)
 
 idiomise : FC -> RawImp -> RawImp
+idiomise fc (IAlternative afc u alts)
+  = IAlternative afc (mapAltType (idiomise afc) u) (idiomise afc <$> alts)
 idiomise fc (IApp afc f a)
     = IApp fc (IApp fc (IVar fc (UN "<*>"))
                     (idiomise afc f))

src/TTImp/BindImplicits.idr

@@ -105,11 +105,7 @@ doBind ns (IQuote fc tm)
 doBind ns (IUnquote fc tm)
     = IUnquote fc (doBind ns tm)
 doBind ns (IAlternative fc u alts)
-    = IAlternative fc (doBindAlt u) (map (doBind ns) alts)
+    = IAlternative fc (mapAltType (doBind ns) u) (map (doBind ns) alts)
-  where
-    doBindAlt : AltType -> AltType
-    doBindAlt (UniqueDefault t) = UniqueDefault (doBind ns t)
-    doBindAlt u = u
 doBind ns tm = tm
 
 export

src/TTImp/TTImp.idr

@@ -379,6 +379,11 @@ data ImpREPL : Type where
      DebugInfo : Name -> ImpREPL
      Quit : ImpREPL
 
+export
+mapAltType : (RawImp -> RawImp) -> AltType -> AltType
+mapAltType f (UniqueDefault x) = UniqueDefault (f x)
+mapAltType _ u = u
+
 export
 lhsInCurrentNS : {auto c : Ref Ctxt Defs} ->
                  NestedNames vars -> RawImp -> Core RawImp

tests/idris2/basic032/Idiom.idr

@@ -12,4 +12,3 @@ export
 
 addm : Maybe Int -> Maybe Int -> Maybe Int
 addm x y = [| x + y |]
-

tests/idris2/basic032/Idiom2.idr

@@ -0,0 +1,17 @@
+-- Things like  ( , )  ( ** )  ()   are special in that they denote more than
+-- one thing at once. () can mean Unit or MkUnit, (,) can mean Pair or MkPair
+-- Idiom brackets need to be able to work despite that, which is tested here
+
+fez : IO Int
+fez = pure 1
+
+fez1 : IO (Int, ())
+fez1 = [| MkPair fez (pure ()) |]
+
+fez2 : IO (Int, Maybe Int)
+fez2 = [| ( fez , (pure Nothing) ) |]
+
+fuzz : IO ()
+fuzz = do
+  fez1 >>= printLn
+  fez2 >>= printLn

tests/idris2/basic032/expected

@@ -1,3 +1,5 @@
 1/1: Building Idiom (Idiom.idr)
 Main> Just 7
 Main> Bye for now!
+(1, ())
+(1, Nothing)

tests/idris2/basic032/run

@@ -1,3 +1,4 @@
 $1 --no-color --console-width 0 --no-banner Idiom.idr < input
+$1 --no-color --console-width 0 --no-banner Idiom2.idr --exec fuzz
 
 rm -rf build