diff --git a/cspell.json b/cspell.json
index f683c1ec..8396695f 100644
--- a/cspell.json
+++ b/cspell.json
@@ -44,6 +44,7 @@
     "inodes",
     "insta",
     "interner",
+    "ints",
     "itertools",
     "ITRS",
     "kwarg",
diff --git a/examples/all_tree.bend b/examples/all_tree.bend
index d70dbd2b..8de2403f 100644
--- a/examples/all_tree.bend
+++ b/examples/all_tree.bend
@@ -16,7 +16,7 @@ def and(a, b):
 def all(tree):
   fold tree:
     case Tree/Node:
-      return and(tree.lft tree.rgt)
+      return and(tree.lft, tree.rgt)
     case Tree/Leaf:
       return tree.val
 
diff --git a/src/imp/parser.rs b/src/imp/parser.rs
index d3991324..b57d2b9e 100644
--- a/src/imp/parser.rs
+++ b/src/imp/parser.rs
@@ -96,6 +96,7 @@ impl<'a> PyParser<'a> {
     let ini_idx = *self.index();
 
     let base = match head {
+      // Tuple or parenthesized expression
       '(' => {
         self.advance_one();
         let head = self.parse_expr(false)?;
@@ -114,41 +115,49 @@ impl<'a> PyParser<'a> {
           head
         }
       }
+      // Map or Sup
       '{' => {
         self.advance_one();
-        self.skip_trivia();
-        if self.try_consume_exactly("}") {
-          return Ok(Expr::MapInit { entries: Vec::new() });
+        // Empty map
+        if self.try_consume("}") {
+          return Ok(Expr::MapInit { entries: vec![] });
         }
         let head = self.parse_expr(false)?;
         self.skip_trivia();
         if self.starts_with(":") { self.parse_map_init(head)? } else { self.parse_sup(head)? }
       }
+      // List or Comprehension
       '[' => self.list_or_comprehension()?,
+      // Symbol
       '`' => Expr::Num { val: Num::U24(self.parse_quoted_symbol()?) },
+      // String
       '\"' => {
         let str = self.parse_quoted_string()?;
         let val = STRINGS.get(str);
         Expr::Str { val }
       }
+      // Char
       '\'' => {
         let chr = self.parse_quoted_char()?;
         Expr::Num { val: Num::U24(chr as u32 & 0x00ff_ffff) }
       }
+      // Unscoped var
       '$' => {
         self.advance_one();
         let nam = self.parse_bend_name()?;
         Expr::Chn { nam }
       }
+      // Era
       '*' => {
         self.advance_one();
         Expr::Eraser
       }
+      // Number
       c if is_num_char(c) => {
         let val = self.parse_number()?;
         Expr::Num { val }
       }
-      // var or postfix
+      // var
       _ => {
         let nam = self.labelled(|p| p.parse_bend_name(), "expression")?;
         Expr::Var { nam }
@@ -178,7 +187,9 @@ impl<'a> PyParser<'a> {
         } else {
           args.push(arg);
         }
-        self.try_consume(",");
+        if !self.starts_with(")") {
+          self.consume(",")?;
+        }
       }
       if args.is_empty() && kwargs.is_empty() {
         return Ok(base);
@@ -202,7 +213,7 @@ impl<'a> PyParser<'a> {
     // ctr
     if self.starts_with("{") {
       if let Expr::Var { nam } = base {
-        let kwargs = self.list_like(|p| p.data_kwarg(), "{", "}", ",", false, 0)?;
+        let kwargs = self.list_like(|p| p.data_kwarg(), "{", "}", ",", true, 0)?;
         return Ok(Expr::Constructor { name: nam, args: Vec::new(), kwargs });
       } else {
         return self.expected_spanned("Constructor name", ini_idx, end_idx);
@@ -218,15 +229,18 @@ impl<'a> PyParser<'a> {
     self.consume(":")?;
     let val = self.parse_expr(false)?;
     entries.push((head, val));
-    self.try_consume(",");
-    let tail = self.list_like(|p| p.parse_map_entry(), "", "}", ",", false, 0)?;
+    self.skip_trivia();
+    if !self.starts_with("}") {
+      self.consume(",")?;
+    }
+    let tail = self.list_like(|p| p.parse_map_entry(), "", "}", ",", true, 0)?;
     entries.extend(tail);
     Ok(Expr::MapInit { entries })
   }
 
   fn parse_sup(&mut self, head: Expr) -> ParseResult<Expr> {
     let mut els = vec![head];
-    let tail = self.list_like(|p| p.parse_expr(false), "", "}", ",", false, 1)?;
+    let tail = self.list_like(|p| p.parse_expr(false), "", "}", ",", true, 1)?;
     els.extend(tail);
     Ok(Expr::Sup { els })
   }
@@ -274,8 +288,11 @@ impl<'a> PyParser<'a> {
     } else {
       // List
       let mut head = vec![head];
-      self.try_consume(",");
-      let tail = self.list_like(|p| p.parse_expr(false), "", "]", ",", false, 0)?;
+      self.skip_trivia();
+      if !self.starts_with("]") {
+        self.consume(",")?;
+      }
+      let tail = self.list_like(|p| p.parse_expr(false), "", "]", ",", true, 0)?;
       head.extend(tail);
       Ok(Expr::Lst { els: head })
     }
@@ -685,7 +702,9 @@ impl<'a> PyParser<'a> {
       while !self.starts_with(":") {
         with.push(self.parse_bend_name()?);
         self.skip_trivia_inline();
-        self.try_consume_exactly(",");
+        if !self.starts_with(":") {
+          self.consume_exactly(",")?;
+        }
         self.skip_trivia_inline();
       }
       with
@@ -721,7 +740,7 @@ impl<'a> PyParser<'a> {
   ///   "else" ":"
   ///     <base>
   fn parse_bend(&mut self, indent: &mut Indent) -> ParseResult<(Stmt, Indent)> {
-    let args = self.list_like(|p| p.parse_match_arg(), "", ":", ",", false, 1)?;
+    let args = self.list_like(|p| p.parse_match_arg(), "", ":", ",", true, 1)?;
     let (bind, init) = args.into_iter().unzip();
     self.consume_new_line()?;
     indent.enter_level();
@@ -822,7 +841,7 @@ impl<'a> PyParser<'a> {
     }
     // Dup pattern
     if self.starts_with("{") {
-      let binds = self.list_like(|p| p.parse_assign_pattern(), "{", "}", "", false, 2)?;
+      let binds = self.list_like(|p| p.parse_assign_pattern(), "{", "}", ",", true, 2)?;
       return Ok(AssignPattern::Sup(binds));
     }
 
@@ -892,7 +911,7 @@ impl<'a> PyParser<'a> {
     let name = self.parse_bend_name()?;
     self.skip_trivia_inline();
     let params = if self.starts_with("(") {
-      self.list_like(|p| p.parse_bend_name(), "(", ")", ",", false, 0)?
+      self.list_like(|p| p.parse_bend_name(), "(", ")", ",", true, 0)?
     } else {
       vec![]
     };
@@ -932,7 +951,7 @@ impl<'a> PyParser<'a> {
       let mut fields = Vec::new();
       self.skip_trivia_inline();
       if self.starts_with("{") {
-        fields = self.list_like(|p| p.parse_variant_field(), "{", "}", ",", false, 0)?;
+        fields = self.list_like(|p| p.parse_variant_field(), "{", "}", ",", true, 0)?;
       }
       variants.push(Variant { name: ctr_name, fields });
       if !self.is_eof() {
@@ -957,7 +976,7 @@ impl<'a> PyParser<'a> {
     let name = self.parse_top_level_name()?;
     self.skip_trivia_inline();
     let fields = if self.starts_with("{") {
-      self.list_like(|p| p.parse_variant_field(), "{", "}", ",", false, 0)?
+      self.list_like(|p| p.parse_variant_field(), "{", "}", ",", true, 0)?
     } else {
       vec![]
     };
diff --git a/tests/golden_tests/parse_file/imp_program.bend b/tests/golden_tests/parse_file/imp_program.bend
index 96bbe87c..fe4312dd 100644
--- a/tests/golden_tests/parse_file/imp_program.bend
+++ b/tests/golden_tests/parse_file/imp_program.bend
@@ -53,17 +53,17 @@ def swt(n):
 
 def fld(list):
   fold list:
-    case List/cons:
+    case List/Cons:
       return 1;
-    case List/nil:
+    case List/Nil:
       return 2;
 
 def bnd():
   bend x = 0:
     when x < 10:
-      return List/cons(x fork(x + 1));
+      return List/Cons(x, fork(x + 1));
     else:
-      return List/nil();
+      return List/Nil();
 
 def era():
   * = (2 + 3)
diff --git a/tests/golden_tests/run_file/fold_with_state.bend b/tests/golden_tests/run_file/fold_with_state.bend
index ee8b980e..c6fcf16a 100644
--- a/tests/golden_tests/run_file/fold_with_state.bend
+++ b/tests/golden_tests/run_file/fold_with_state.bend
@@ -1,7 +1,7 @@
 def main:
   y = 1
-  fold x = [0 0 0] with y:
+  fold x = [0, 0, 0] with y:
     case List/Cons:
-      return List/Cons(x.head + y x.tail(y + 1))
+      return List/Cons(x.head + y, x.tail(y + 1))
     case List/Nil:
       return List/Nil
diff --git a/tests/golden_tests/run_file/imp_empty_list.bend b/tests/golden_tests/run_file/imp_empty_list.bend
deleted file mode 100644
index 134f1b09..00000000
--- a/tests/golden_tests/run_file/imp_empty_list.bend
+++ /dev/null
@@ -1,2 +0,0 @@
-def main:
-  return []
\ No newline at end of file
diff --git a/tests/golden_tests/run_file/imp_empty_literals.bend b/tests/golden_tests/run_file/imp_empty_literals.bend
new file mode 100644
index 00000000..a8f235b8
--- /dev/null
+++ b/tests/golden_tests/run_file/imp_empty_literals.bend
@@ -0,0 +1,11 @@
+def list:
+  return []
+
+def map:
+  return {}
+
+def str:
+  return ""
+
+def main:
+  return []
\ No newline at end of file
diff --git a/tests/snapshots/parse_file__imp_program.bend.snap b/tests/snapshots/parse_file__imp_program.bend.snap
index d9b6a29a..ab1d9e14 100644
--- a/tests/snapshots/parse_file__imp_program.bend.snap
+++ b/tests/snapshots/parse_file__imp_program.bend.snap
@@ -26,14 +26,18 @@ input_file: tests/golden_tests/parse_file/imp_program.bend
 
 (swt) = λ%arg0 use n = %arg0; switch n = n { 0: 42; _ n-1: 1; }
 
-(fld) = λ%arg0 use list = %arg0; fold list = list { List/cons: 1; List/nil: 2; }
+(fld) = λ%arg0 use list = %arg0; fold list = list { List/Cons: 1; List/Nil: 2; }
 
-(bnd) = bend x = 0, { when (< x 10): (List/cons x (fork (+ x 1))); else: List/nil }
+(bnd) = bend x = 0, { when (< x 10): (List/Cons x (fork (+ x 1))); else: List/Nil }
 
 (era) = let * = (+ 2 3); let the_expr_killer = *; (the_expr_killer 9)
 
 (main) = do IO { ask x = IO.read; x }
 
+(List/Cons) = λhead λtail λList/Cons λList/Nil (List/Cons head tail)
+
+(List/Nil) = λList/Cons λList/Nil List/Nil
+
 (Map/Node) = λvalue λleft λright λMap/Node λMap/Leaf (Map/Node value left right)
 
 (Map/Leaf) = λMap/Node λMap/Leaf Map/Leaf
diff --git a/tests/snapshots/run_file__imp_empty_literals.bend.snap b/tests/snapshots/run_file__imp_empty_literals.bend.snap
new file mode 100644
index 00000000..43a42a13
--- /dev/null
+++ b/tests/snapshots/run_file__imp_empty_literals.bend.snap
@@ -0,0 +1,5 @@
+---
+source: tests/golden_tests.rs
+input_file: tests/golden_tests/run_file/imp_empty_literals.bend
+---
+λ* λa a