diff --git a/src/musique.hh b/src/musique.hh
index 25d0bee..670d7a5 100644
--- a/src/musique.hh
+++ b/src/musique.hh
@@ -321,8 +321,9 @@ struct Ast
 {
 	// Named constructors of AST structure
 	static Ast binary(Token, Ast lhs, Ast rhs);
-	static Ast block(Location location, Ast seq = sequence({}), std::vector<Ast> parameters = {});
+	static Ast block(Location location, Ast seq = sequence({}));
 	static Ast call(std::vector<Ast> call);
+	static Ast lambda(Location location, Ast seq = sequence({}), std::vector<Ast> parameters = {});
 	static Ast literal(Token);
 	static Ast sequence(std::vector<Ast> call);
 	static Ast variable_declaration(Location loc, std::vector<Ast> lvalues, std::optional<Ast> rvalue);
@@ -331,6 +332,7 @@ struct Ast
 	{
 		Binary,               // Binary operator application like `1` + `2`
 		Block,                // Block expressions like `[42; hello]`
+		Lambda,               // Block expression beeing functions like `[i|i+1]`
 		Call,                 // Function call application like `print 42`
 		Literal,              // Compile time known constant like `c` or `1`
 		Sequence,             // Several expressions sequences like `42`, `42; 32`
@@ -418,9 +420,19 @@ struct Number
 std::ostream& operator<<(std::ostream& os, Number const& num);
 
 struct Value;
+struct Interpreter;
 
 using Function = std::function<Result<Value>(std::vector<Value>)>;
 
+struct Lambda
+{
+	Location location;
+	std::vector<std::string> parameters;
+	Ast body;
+
+	Result<Value> operator()(Interpreter &i, std::vector<Value> params);
+};
+
 template<typename T, typename ...XS>
 constexpr auto is_one_of = (std::is_same_v<T, XS> || ...);
 
diff --git a/src/parser.cc b/src/parser.cc
index 0b431ee..b5e4161 100644
--- a/src/parser.cc
+++ b/src/parser.cc
@@ -102,18 +102,30 @@ Result<Ast> Parser::parse_atomic_expression()
 
 			auto start = token_id;
 			std::vector<Ast> parameters;
+			bool is_lambda = false;
 
-			if (auto p = parse_many(*this, &Parser::parse_identifier_with_trailing_separators, std::nullopt, At_Least::One); p && expect(Token::Type::Parameter_Separator)) {
+			if (expect(Token::Type::Parameter_Separator)) {
 				consume();
-				parameters = std::move(p).value();
+				is_lambda = true;
 			} else {
-				token_id = start;
+				auto p = parse_many(*this, &Parser::parse_identifier_with_trailing_separators, std::nullopt, At_Least::One);
+				if (p && expect(Token::Type::Parameter_Separator)) {
+					consume();
+					parameters = std::move(p).value();
+					is_lambda = true;
+				} else {
+					token_id = start;
+				}
 			}
 
 			return parse_sequence().and_then([&](Ast &&ast) -> Result<Ast> {
 				Try(ensure(Token::Type::Close_Block));
 				consume();
-				return Ast::block(opening.location, std::move(ast), std::move(parameters));
+				if (is_lambda) {
+					return Ast::lambda(opening.location, std::move(ast), std::move(parameters));
+				} else {
+					return Ast::block(opening.location, std::move(ast));
+				}
 			});
 		}
 
@@ -253,16 +265,25 @@ Ast Ast::sequence(std::vector<Ast> expressions)
 	return ast;
 }
 
-Ast Ast::block(Location location, Ast seq, std::vector<Ast> parameters)
+Ast Ast::block(Location location, Ast seq)
 {
 	Ast ast;
 	ast.type = Type::Block;
 	ast.location = location;
-	ast.arguments = std::move(parameters);
 	ast.arguments.push_back(std::move(seq));
 	return ast;
 }
 
+Ast Ast::lambda(Location location, Ast body, std::vector<Ast> parameters)
+{
+	Ast ast;
+	ast.type = Type::Lambda;
+	ast.location = location;
+	ast.arguments = std::move(parameters);
+	ast.arguments.push_back(std::move(body));
+	return ast;
+}
+
 Ast Ast::variable_declaration(Location loc, std::vector<Ast> lvalues, std::optional<Ast> rvalue)
 {
 	Ast ast;
@@ -300,6 +321,7 @@ bool operator==(Ast const& lhs, Ast const& rhs)
 
 	case Ast::Type::Block:
 	case Ast::Type::Call:
+	case Ast::Type::Lambda:
 	case Ast::Type::Sequence:
 	case Ast::Type::Variable_Declaration:
 		return lhs.arguments.size() == rhs.arguments.size()
@@ -315,6 +337,7 @@ std::ostream& operator<<(std::ostream& os, Ast::Type type)
 	case Ast::Type::Binary:               return os << "BINARY";
 	case Ast::Type::Block:                return os << "BLOCK";
 	case Ast::Type::Call:                 return os << "CALL";
+	case Ast::Type::Lambda:               return os << "LAMBDA";
 	case Ast::Type::Literal:              return os << "LITERAL";
 	case Ast::Type::Sequence:             return os << "SEQUENCE";
 	case Ast::Type::Variable_Declaration: return os << "VAR";
diff --git a/src/tests/parser.cc b/src/tests/parser.cc
index ec4c2c5..81e25b0 100644
--- a/src/tests/parser.cc
+++ b/src/tests/parser.cc
@@ -139,9 +139,9 @@ suite parser_test = [] {
 			Ast::literal({ Token::Type::Symbol, "i", {} }),
 			Ast::literal({ Token::Type::Symbol, "j", {} }),
 			Ast::literal({ Token::Type::Symbol, "k", {} })
-		}), {}));
+		})));
 
-		expect_ast("[ i j k | i + j + k ]", Ast::block({}, Ast::binary(
+		expect_ast("[ i j k | i + j + k ]", Ast::lambda({}, Ast::binary(
 			{ Token::Type::Operator, "+", {} },
 			Ast::literal({ Token::Type::Symbol, "i", {} }),
 			Ast::binary(
@@ -155,7 +155,7 @@ suite parser_test = [] {
 			Ast::literal({ Token::Type::Symbol, "k", {} })
 		}));
 
-		expect_ast("[ i; j; k | i + j + k ]", Ast::block({}, Ast::binary(
+		expect_ast("[ i; j; k | i + j + k ]", Ast::lambda({}, Ast::binary(
 			{ Token::Type::Operator, "+", {} },
 			Ast::literal({ Token::Type::Symbol, "i", {} }),
 			Ast::binary(
@@ -168,6 +168,8 @@ suite parser_test = [] {
 			Ast::literal({ Token::Type::Symbol, "j", {} }),
 			Ast::literal({ Token::Type::Symbol, "k", {} })
 		}));
+
+		expect_ast("[|1]", Ast::lambda({}, Ast::literal({ Token::Type::Numeric, "1", {} }), {}));
 	};
 
 	"Variable declarations"_test = [] {