List Literal Patterns

.gitignore

@@ -3,6 +3,7 @@
 build/
 out/
 project/target/
+project/project
 target/
 drafts/
 node_modules/
@@ -12,6 +13,7 @@ licenses/
 .bsp/
 bin
 .metals/
+project/metals.sbt
 .vscode/
 .bloop/
 *.tgz

effekt/jvm/src/test/scala/effekt/ParserTests.scala

@@ -623,6 +623,23 @@ class ParserTests extends munit.FunSuite {
       parseMatchPattern("_"),
       IgnorePattern(Span.missing))
     parseMatchPattern("Cons(x, Cons(x, Nil()))")
+    parseMatchPattern("[]")
+    parseMatchPattern("[1]")
+    parseMatchPattern("[_, 2, (3, 4)]")
+    parseMatchPattern("[[1, 2], [3, [4, (6, [7, 8])]]]")
+
+    {
+      def cons(head: MatchPattern, tail: MatchPattern) =
+        TagPattern(IdRef(Nil, "Cons", Span.missing), List(head, tail), Span.missing)
+      def nil = TagPattern(IdRef(Nil, "Nil", Span.missing), Nil, Span.missing)
+      def lit(l: Int) =
+        LiteralPattern(Literal(l, symbols.builtins.TInt, Span.missing), Span.missing)
+
+      assertEqualModuloSpans(
+        parseMatchPattern("[1, [2, 3, 4], [5]]"),
+        cons(lit(1), cons(cons(lit(2), cons(lit(3), cons(lit(4), nil))), cons(cons(lit(5), nil), nil)))
+      )
+    }
 
     {
       val (source, pos) =

effekt/shared/src/main/scala/effekt/Parser.scala

@@ -1018,8 +1018,15 @@ class Parser(tokens: Seq[Token], source: Source) {
           case Many(p :: Nil , _) => fail("Pattern matching on tuples requires more than one element")
           case Many(ps, _) => TagPattern(IdRef(List("effekt"), s"Tuple${ps.size}", span().synthesized), ps, span())
         }
+        case `[` => manyTrailing(matchPattern, `[`, `,`, `]`).foldRight(NilPattern)(ConsPattern)
         case k => fail("pattern", k)
       }
+
+  private def NilPattern: MatchPattern =
+    TagPattern(IdRef(Nil, "Nil", span().synthesized), Nil, span())
+
+  private def ConsPattern(head: MatchPattern, tail: MatchPattern): MatchPattern =
+    TagPattern(IdRef(Nil, "Cons", span().synthesized), List(head, tail), span())
 
   def matchExpr(scrutinee: Term): Term =
       val clauses = `match` ~> braces { manyWhile(matchClause(), `case`) }

examples/neg/parsing/invalid_lit_list_pattern.check

@@ -0,0 +1,3 @@
+[error] examples/neg/parsing/invalid_lit_list_pattern.effekt:3:17: Expected ] but got )
+  case [1, [2, 3)] => ()
+                ^

examples/neg/parsing/invalid_lit_list_pattern.effekt

@@ -0,0 +1,5 @@
+val _ = [] match {
+  case [] => ()
+  case [1, [2, 3)] => ()
+  case _ => ()
+}