fix #363 comma-first sequence notation

parser-typechecker/src/Unison/TermParser.hs

@@ -205,9 +205,11 @@ placeholder :: Var v => TermP v
 placeholder = (\t -> Term.placeholder (ann t) (L.payload t)) <$> blank
 
 vector :: Var v => TermP v -> TermP v
-vector p = f <$> reserved "[" <*> elements <*> reserved "]"
+vector p = f <$> reserved "[" <*> elements <*> trailing
   where
-    elements = sepBy (reserved ",") p
+    trailing = optional semi *> reserved "]"
+    sep = P.try $ optional semi *> reserved "," <* optional semi
+    elements = sepBy sep p
     f open elems close = Term.vector (ann open <> ann close) elems
 
 termLeaf :: forall v. Var v => TermP v

unison-src/tests/sequence-literal.u

@@ -0,0 +1,19 @@
+a = [1,2,3]
+b = [1 ,2 ,3
+    ]
+c = [ 1 , 2 , 3 ]
+d = [ 1
+    , 2
+    , 3 ]
+e = [ 1
+    , 2
+    , 3
+    ]
+f =
+  [ 1
+  , 2
+  , 3
+  ]
+g = [ 1
+    , 2,
+    3 ]