func TestLambda(t *testing.T) { env := environment.New(nil) environment.Define(env, &types.Symbol{"+"}, &types.Builtin{add}) environment.Define(env, &types.Symbol{"begin"}, &types.Builtin{begin}) f, _ := parser.Parse(strings.NewReader("(lambda (n) n)")) if a, err := Eval(env, f); err != nil { t.Error("Evaluating lambda failed:", err, f) } else if !types.IsSFunction(a) { t.Error("Evaluating lambda didn't return an SFunction:", a) } f, _ = parser.Parse(strings.NewReader("(define add1 (lambda (n) (+ 1 n)))")) if _, err := Eval(env, f); err != nil { t.Error("Evaluating define lambda failed:", err) } if a, err := environment.Get(env, &types.Symbol{"add1"}); err != nil { t.Error("'Get'ting add1 caused an error: ", err) } else if !types.IsSFunction(a) { t.Error("add1 is not an SFunction:", a) } f, _ = parser.Parse(strings.NewReader("(add1 1)")) if a, err := Eval(env, f); err != nil { t.Error("Evaluating (add1 1) failed:", err) } else if !types.Eqv(a, &types.Number{2}) { t.Error("(add1 1) != 2", a) } }
func TestDefine(t *testing.T) { env := environment.New(nil) f, _ := parser.Parse(strings.NewReader("(define answer 42)")) if _, err := Eval(env, f); err != nil { t.Error("Evaluating (define answer 42) failed:", err) } if a, err := environment.Get(env, &types.Symbol{"answer"}); err != nil { t.Error("'Get'ting 'answer' caused an error: ", err) } else if !types.Eqv(a, &types.Number{42}) { t.Error("answer != 42", a) } }
func Eval(env *environment.Environment, f types.Type) (types.Type, error) { if types.IsPair(f) { car, err := types.Car(f) if err != nil { return nil, err } cdr, err := types.Cdr(f) if err != nil { return nil, err } return Apply(env, car, cdr) } if types.IsSymbol(f) { return environment.Get(env, f.(*types.Symbol)) } return f, nil }