ast: fn init

2 files changed, 193 insertions, 117 deletions

diff --git a/evaluator/evaluator.go b/evaluator/evaluator.go
index 9cead89..f765d02 100644
--- a/evaluator/evaluator.go
+++ b/evaluator/evaluator.go
@@ -1,9 +1,9 @@
 package evaluator
 
 import (
+	"fmt"
 	"mana/ast"
 	"mana/object"
-  "fmt"
 )
 
 var (
@@ -25,15 +25,15 @@ func Eval(node ast.Node, env *object.Environment) object.Object {
 	case *ast.BlockStatement:
 		return evalBlockStatement(node, env)
 
-  case *ast.LetStatement:
-    val := Eval(node.Value, env)
-    if isError(val) {
-      return val
-    }
-    env.Set(node.Name.Value, val)
+	case *ast.LetStatement:
+		val := Eval(node.Value, env)
+		if isError(val) {
+			return val
+		}
+		env.Set(node.Name.Value, val)
 
-  case *ast.Identifier:
-    return evalIdentifier(node, env)
+	case *ast.Identifier:
+		return evalIdentifier(node, env)
 
 	// Expressions
 	case *ast.IntegerLiteral:
@@ -44,30 +44,48 @@ func Eval(node ast.Node, env *object.Environment) object.Object {
 
 	case *ast.PrefixExpression:
 		right := Eval(node.Right, env)
-    if isError(right) {
-      return right
-    }
+		if isError(right) {
+			return right
+		}
 		return evalPrefixExpression(node.Operator, right)
 
 	case *ast.InfixExpression:
 		left := Eval(node.Left, env)
-    if isError(left) {
-      return left
-    }
+		if isError(left) {
+			return left
+		}
 		right := Eval(node.Right, env)
-    if isError(right) {
-      return right
-    }
+		if isError(right) {
+			return right
+		}
 		return evalInfixExpression(node.Operator, left, right)
 
 	case *ast.IfExpression:
 		return evalIfExpression(node, env)
 
+	case *ast.CallExpression:
+		function := Eval(node.Function, env)
+
+		if isError(function) {
+			return function
+		}
+
+		args := evalExpressions(node.Arguments, env)
+		if len(args) == 1 && isError(args[0]) {
+			return args[0]
+		}
+
+	case *ast.FunctionLiteral:
+		params := node.Parameters
+		body := node.Body
+
+		return &object.Function{Parameters: params, Body: body, Env: env}
+
 	case *ast.ReturnStatement:
 		val := Eval(node.ReturnValue, env)
-    if isError(val) {
-      return val
-    }
+		if isError(val) {
+			return val
+		}
 		return &object.ReturnValue{Value: val}
 	}
 
@@ -80,30 +98,44 @@ func evalProgram(program *ast.Program, env *object.Environment) object.Object {
 	for _, statement := range program.Statements {
 		result = Eval(statement, env)
 
-    switch result := result.(type) {
-    case *object.ReturnValue:
-      return result.Value
-    case *object.Error:
-      return result
-    }
+		switch result := result.(type) {
+		case *object.ReturnValue:
+			return result.Value
+		case *object.Error:
+			return result
+		}
 	}
 
 	return result
 }
 
-
 func evalBlockStatement(block *ast.BlockStatement, env *object.Environment) object.Object {
 	var result object.Object
 
 	for _, statement := range block.Statements {
 		result = Eval(statement, env)
 
-    if result != nil {
-      rt := result.Type()
-      if rt == object.RETURN_VALUE_OBJ || rt == object.ERROR_OBJ {
-        return result
-      }
-    }
+		if result != nil {
+			rt := result.Type()
+			if rt == object.RETURN_VALUE_OBJ || rt == object.ERROR_OBJ {
+				return result
+			}
+		}
+	}
+
+	return result
+}
+
+func evalExpressions(exps []ast.Expression, env *object.Environment) []object.Object {
+	var result []object.Object
+
+	for _, e := range exps {
+		evaluated := Eval(e, env)
+		if isError(evaluated) {
+			return []object.Object{evaluated}
+		}
+
+		result = append(result, evaluated)
 	}
 
 	return result
@@ -123,7 +155,7 @@ func evalPrefixExpression(operator string, right object.Object) object.Object {
 	case "-":
 		return evalMinusPrefixOperatorExpression(right)
 	default:
-    return newError("unknown operator: %s%s", operator, right.Type())
+		return newError("unknown operator: %s%s", operator, right.Type())
 	}
 }
 
@@ -135,10 +167,10 @@ func evalInfixExpression(operator string, left, right object.Object) object.Obje
 		return nativeBoolToBooleanObject(left == right)
 	case operator == "!=":
 		return nativeBoolToBooleanObject(left != right)
-  case left.Type() != right.Type():
-    return newError("type mismatch: %s %s %s", left.Type(), operator, right.Type())
+	case left.Type() != right.Type():
+		return newError("type mismatch: %s %s %s", left.Type(), operator, right.Type())
 	default:
-		return newError("unknown operator: %s %s %s", left.Type(), operator, right.Type()) 
+		return newError("unknown operator: %s %s %s", left.Type(), operator, right.Type())
 	}
 }
 
@@ -195,9 +227,9 @@ func evalIntegerInfixExpression(operator string, left, right object.Object) obje
 
 func evalIfExpression(ie *ast.IfExpression, env *object.Environment) object.Object {
 	condition := Eval(ie.Condition, env)
-  if isError(condition) {
-    return condition
-  }
+	if isError(condition) {
+		return condition
+	}
 	if isTruthy(condition) {
 		return Eval(ie.Consequence, env)
 	} else if ie.Alternative != nil {
@@ -208,11 +240,11 @@ func evalIfExpression(ie *ast.IfExpression, env *object.Environment) object.Obje
 }
 
 func evalIdentifier(node *ast.Identifier, env *object.Environment) object.Object {
-  val, ok := env.Get(node.Value)
-  if !ok {
-    return newError("identifier not found: " + node.Value)
-  }
-  return val
+	val, ok := env.Get(node.Value)
+	if !ok {
+		return newError("identifier not found: " + node.Value)
+	}
+	return val
 }
 
 func isTruthy(obj object.Object) bool {
@@ -229,12 +261,12 @@ func isTruthy(obj object.Object) bool {
 }
 
 func newError(format string, a ...interface{}) *object.Error {
-  return &object.Error{Message: fmt.Sprintf(format, a...)}
+	return &object.Error{Message: fmt.Sprintf(format, a...)}
 }
 
 func isError(obj object.Object) bool {
-  if obj != nil {
-    return obj.Type() == object.ERROR_OBJ
-  }
-  return false
+	if obj != nil {
+		return obj.Type() == object.ERROR_OBJ
+	}
+	return false
 }
diff --git a/evaluator/evaluator_test.go b/evaluator/evaluator_test.go
index 38fed91..f83cf7f 100644
--- a/evaluator/evaluator_test.go
+++ b/evaluator/evaluator_test.go
@@ -5,7 +5,7 @@ import (
 	"mana/object"
 	"mana/parser"
 
-  "testing"
+	"testing"
 )
 
 func TestEvalIntegerExpression(t *testing.T) {
@@ -138,36 +138,36 @@ func TestReturnStatements(t *testing.T) {
 }
 
 func TestErrorhandling(t *testing.T) {
-  tests := [] struct {
-    input string
-    expectedMessage string
-  } {
-    {
-      "5 + true;",
-      "type mismatch: INTEGER + BOOLEAN",
-    },
-    {
-      "5 + true; 5;",
-      "type mismatch: INTEGER + BOOLEAN",
-    },
-    {
-      "-true",
-      "unknown operator: -BOOLEAN",
-    },
-    {
-      "true + false;",
-      "unknown operator: BOOLEAN + BOOLEAN",
-    },
-    {
-      "5; true + false; 5",
-      "unknown operator: BOOLEAN + BOOLEAN",
-    },
-    {
-      "if (10 > 1) { true + false; }",
-      "unknown operator: BOOLEAN + BOOLEAN",
-    },
-    {
-      `
+	tests := []struct {
+		input           string
+		expectedMessage string
+	}{
+		{
+			"5 + true;",
+			"type mismatch: INTEGER + BOOLEAN",
+		},
+		{
+			"5 + true; 5;",
+			"type mismatch: INTEGER + BOOLEAN",
+		},
+		{
+			"-true",
+			"unknown operator: -BOOLEAN",
+		},
+		{
+			"true + false;",
+			"unknown operator: BOOLEAN + BOOLEAN",
+		},
+		{
+			"5; true + false; 5",
+			"unknown operator: BOOLEAN + BOOLEAN",
+		},
+		{
+			"if (10 > 1) { true + false; }",
+			"unknown operator: BOOLEAN + BOOLEAN",
+		},
+		{
+			`
       if (10 > 1) {
         if (10 > 1) {
           return true + false;
@@ -175,50 +175,94 @@ func TestErrorhandling(t *testing.T) {
         return 1;
       }
       `,
-      "unknown operator: BOOLEAN + BOOLEAN",
-    },
-    {
-      "foobar",
-      "identifier not found: foobar",
-    },
-  }
-
-  for _, tt := range tests {
-    evaluated := testEval(tt.input)
-
-    errObj, ok := evaluated.(*object.Error)
-    if !ok {
-      t.Errorf("no error object returned. got=%T(%+v)", evaluated, evaluated)
-      continue
-    }
-
-    if errObj.Message != tt.expectedMessage {
-      t.Errorf("wrong error message. expected=%q, got=%q", tt.expectedMessage, errObj.Message)
-    }
-  }
+			"unknown operator: BOOLEAN + BOOLEAN",
+		},
+		{
+			"foobar",
+			"identifier not found: foobar",
+		},
+	}
+
+	for _, tt := range tests {
+		evaluated := testEval(tt.input)
+
+		errObj, ok := evaluated.(*object.Error)
+		if !ok {
+			t.Errorf("no error object returned. got=%T(%+v)", evaluated, evaluated)
+			continue
+		}
+
+		if errObj.Message != tt.expectedMessage {
+			t.Errorf("wrong error message. expected=%q, got=%q", tt.expectedMessage, errObj.Message)
+		}
+	}
 }
 
 func TestLetStatements(t *testing.T) {
-  tests := []struct {
-    input string
-    expected int64
-  } {
-    {"let a = 5; a;", 5},
-    {"let a = 5 * 5; a;", 25},
-    {"let a = 5; let b = a; b;", 5},
-    {"let a = 5; let b = a; let c = a + b + 5; c;", 15},
-  }
-
-  for _, tt := range tests {
-    testIntegerObject(t, testEval(tt.input), tt.expected)
-  }
+	tests := []struct {
+		input    string
+		expected int64
+	}{
+		{"let a = 5; a;", 5},
+		{"let a = 5 * 5; a;", 25},
+		{"let a = 5; let b = a; b;", 5},
+		{"let a = 5; let b = a; let c = a + b + 5; c;", 15},
+	}
+
+	for _, tt := range tests {
+		testIntegerObject(t, testEval(tt.input), tt.expected)
+	}
+}
+
+func TestFunctionObject(t *testing.T) {
+	input := "fn(x) { x + 2; };"
+
+	evaluated := testEval(input)
+
+	fn, ok := evaluated.(*object.Function)
+
+	if !ok {
+		t.Fatalf("object is not Function. got=%T (%+v)", evaluated, evaluated)
+	}
+
+	if len(fn.Parameters) != 1 {
+		t.Fatalf("function has wrong parameters. Parameters=%+v", fn.Parameters)
+	}
+
+	if fn.Parameters[0].String() != "x" {
+		t.Fatalf("parameter is not 'x'. got=%q", fn.Parameters[0])
+	}
+
+	expectedBody := "(x + 2)"
+
+	if fn.Body.String() != expectedBody {
+		t.Fatalf("body is not %q. got=%q", expectedBody, fn.Body.String())
+	}
+}
+
+func TestFunctionApplication(t *testing.T) {
+	tests := []struct {
+		input    string
+		expected int64
+	}{
+		{"let identity = fn(x) { x; }; identity(5);", 5},
+		{"let identity = fn(x) { return x; }; identity(5);", 5},
+		{"let double = fn(x) { x * 2; }; double(5);", 10},
+		{"let add = fn(x, y) { x + y; }; add(5, 5);", 10},
+		{"let add = fn(x, y) { x + y; }; add(5 + 5, add(5, 5));", 20},
+		{"fn(x) { x; }(5)", 5},
+	}
+
+	for _, tt := range tests {
+		testIntegerObject(t, testEval(tt.input), tt.expected)
+	}
 }
 
 func testEval(input string) object.Object {
 	l := lexer.New(input)
 	p := parser.New(l)
 	program := p.ParseProgram()
-  env := object.NewEnvironment()
+	env := object.NewEnvironment()
 
 	return Eval(program, env)
 }