diff --git a/Test/Lexer.lean b/Test/Lexer.lean
index 7865406..e43dd16 100644
--- a/Test/Lexer.lean
+++ b/Test/Lexer.lean
@@ -28,6 +28,12 @@ def lexResult (s : String) : String :=
 #guard_msgs in
 #eval lexResult ":"
 
+/--
+  info: "Value: `,`, Kind: comma"
+-/
+#guard_msgs in
+#eval lexResult ","
+
 /--
   info: "Value: `:`, Kind: colon"
 -/
@@ -339,3 +345,63 @@ def lexResult (s : String) : String :=
 -/
 #guard_msgs in
 #eval lexResult "^ foo"
+
+/--
+  info: "Value: `0`, Kind: intLit"
+-/
+#guard_msgs in
+#eval lexResult "0x"
+
+/--
+  info: "Value: `0`, Kind: intLit"
+-/
+#guard_msgs in
+#eval lexResult "0xi"
+
+/--
+  info: "Value: `0x0123456789abcdefABCDEF`, Kind: intLit"
+-/
+#guard_msgs in
+#eval lexResult "0x0123456789abcdefABCDEF"
+
+/--
+  info: "Value: `42`, Kind: intLit"
+-/
+#guard_msgs in
+#eval lexResult "42"
+
+/--
+  info: "Value: `42.`, Kind: floatLit"
+-/
+#guard_msgs in
+#eval lexResult "42."
+
+/--
+  info: "Value: `42.0`, Kind: floatLit"
+-/
+#guard_msgs in
+#eval lexResult "42.0"
+
+/--
+  info: "Value: `3.1415926`, Kind: floatLit"
+-/
+#guard_msgs in
+#eval lexResult "3.1415926"
+
+/--
+  info: "Value: `34.e0`, Kind: floatLit"
+-/
+#guard_msgs in
+#eval lexResult "34.e0"
+
+/--
+  info: "Value: `34.e-23`, Kind: floatLit"
+-/
+#guard_msgs in
+#eval lexResult "34.e-23"
+
+/--
+  info: "Value: `34.e12`, Kind: floatLit"
+-/
+#guard_msgs in
+#eval lexResult "34.e12"
diff --git a/Veir/ForLean.lean b/Veir/ForLean.lean
index 5a2a8b7..5e98b3b 100644
--- a/Veir/ForLean.lean
+++ b/Veir/ForLean.lean
@@ -16,6 +16,10 @@ def UInt8.isDigit (c : UInt8) : Bool :=
 def UInt8.isHexDigit (c : UInt8) : Bool :=
   c.isDigit || (c >= 'a'.toUInt8 && c <= 'f'.toUInt8) || (c >= 'A'.toUInt8 && c <= 'F'.toUInt8)
 
+@[inline]
+def ByteArray.getD (ba : ByteArray) (i : Nat) (default : UInt8) : UInt8 :=
+  if h : i < ba.size then ba[i] else default
+
 set_option warn.sorry false in
 @[grind .]
 theorem Array.back_popWhile {as : Array α} {p : α → Bool} (h : 0 < (as.popWhile p).size) :
diff --git a/Veir/Parser/Lexer.lean b/Veir/Parser/Lexer.lean
index 4f2e99b..afab109 100644
--- a/Veir/Parser/Lexer.lean
+++ b/Veir/Parser/Lexer.lean
@@ -107,7 +107,7 @@ inductive TokenKind
   | fileMetadataBegin
   /-- The `#-}` token. -/
   | fileMetadataEnd
-deriving Inhabited, Repr
+deriving Inhabited, Repr, DecidableEq
 
 instance TokenKind.toString : ToString TokenKind where
   toString
@@ -315,6 +315,80 @@ def lexPrefixedIdentifier (state : LexerState) (tokStart : Nat)
     else
       .error errorString
 
+/--
+  Lex a number literal.
+
+  integer-literal ::= digit+ | `0x` hex_digit+
+  float-literal ::= [0-9]+[.][0-9]*([eE][-+]?[0-9]+)?
+-/
+def lexNumber (state : LexerState) (firstChar : UInt8) (tokStart : Nat) : Token × LexerState := Id.run do
+  let mut pos := state.pos
+  let input := state.input
+
+  if h: state.isEof then
+    return (state.mkToken .intLit tokStart, state)
+  else
+    let c1 := input[pos]'(by grind [LexerState.isEof])
+    -- Hexadecimal literal
+    if firstChar == '0'.toUInt8 && c1 == 'x'.toUInt8 then
+      -- In MLIR, `0xi` is parsed as `0` followed by `xi`.
+      if !(input.getD (pos + 1) 0).isHexDigit then
+        return (state.mkToken .intLit tokStart, state)
+      pos := pos + 2
+      while h: pos < input.size do
+        let c := input[pos]
+        if c.isHexDigit then
+          pos := pos + 1
+        else
+          break
+      let newState := { state with pos := pos }
+      return (newState.mkToken .intLit tokStart, newState)
+
+    -- Handle the normal decimal case, with the starting digits
+    while h: pos < input.size do
+      let c := input[pos]
+      if UInt8.isDigit c then
+        pos := pos + 1
+      else
+        break
+
+    -- Check for fractional part
+    if input.getD pos 0 != '.'.toUInt8 then
+      let newState := { state with pos := pos }
+      return (newState.mkToken .intLit tokStart, newState)
+    pos := pos + 1
+
+    -- Parse the fractional digits
+    while h: pos < input.size do
+      let c := input[pos]
+      if UInt8.isDigit c then
+        pos := pos + 1
+      else
+        break
+
+    -- Check for exponent part
+    if input.getD pos 0 != 'e'.toUInt8 && input.getD pos 0 != 'E'.toUInt8 then
+      let newState := { state with pos := pos }
+      return (newState.mkToken .floatLit tokStart, newState)
+    pos := pos + 1
+
+    if (input.getD pos 0).isDigit ||
+       ((input.getD pos 0 == '+'.toUInt8 || input.getD pos 0 == '-'.toUInt8) &&
+       (input.getD (pos + 1) 0).isDigit) then
+      pos := pos + 1
+      while h: pos < input.size do
+        let c := input[pos]
+        if UInt8.isDigit c then
+          pos := pos + 1
+        else
+          break
+      let newState := { state with pos := pos }
+      return (newState.mkToken .floatLit tokStart, newState)
+    else
+      let newState := { state with pos := pos }
+      return (newState.mkToken .floatLit tokStart, newState)
+
+
 /--
   Lex the next token from the input.
 -/
@@ -336,6 +410,9 @@ partial def lex (state : LexerState) : Except String (Token × LexerState) :=
     else if c == ':'.toUInt8 then
       let newState := { state with pos := state.pos + 1 }
       return (newState.mkToken .colon tokStart, newState)
+    else if c == ','.toUInt8 then
+      let newState := { state with pos := state.pos + 1 }
+      return (newState.mkToken .comma tokStart, newState)
     else if c == '('.toUInt8 then
       let newState := { state with pos := state.pos + 1 }
       return (newState.mkToken .lParen tokStart, newState)
@@ -447,6 +524,9 @@ partial def lex (state : LexerState) : Except String (Token × LexerState) :=
     else if c == '!'.toUInt8 then
       let newState := { state with pos := state.pos + 1 }
       lexPrefixedIdentifier newState tokStart .exclamationIdent
+    else if UInt8.isDigit c then
+      let newState := { state with pos := state.pos + 1 }
+      return lexNumber newState c tokStart
     else
       .error s!"Unexpected character '{Char.ofUInt8 c}' at position {state.pos}"