Question

我为此使用lang pl。我已经实现了语言“ ROL”，现在我正尝试扩展该语言以使用替代模型来支持乐趣和通话。我的基本代码如下。我所有的旧测试都通过了，所以我猜没有编译问题。我有3个针对“有趣”和“通话”的新测试，这些测试一直给我一个错误。我在打电话给functiom时遇到了麻烦。

(define-type RegE
[Reg Bit-List]
[And RegE RegE]
[Or RegE RegE]
[Shl RegE]
[Id Symbol]
[With Symbol RegE RegE]
[Bool Boolean]
[Geq RegE RegE]
[Maj RegE]
[If RegE RegE RegE]
[Fun Symbol RegE]
[Call RegE RegE])


(define-type RES
[RES_Bool Boolean]
[RegV Bit-List]
[FunV Symbol RegE])

评估：

(: eval : RegE -> RES)
;; evaluates RegE expressions by reducing them to bit-lists
(define (eval expr)
  (cases expr
    ...
    [(With bound-id named-expr bound-body)
       (eval (subst bound-body
                    bound-id
                    (Reg (RegV->bit-list(eval named-expr)))))]
    [(Fun bound-id bound-body) (FunV bound-id bound-body)]
    [(Call fun-expr arg-expr)
       (let ([fval (eval fun-expr)])
         (cases fval
           [(FunV bound-id bound-body)
            (eval (subst bound-body
                   bound-id
                   arg-expr))]
           [else (error 'eval "`call' expects a function, got: ~s"
                              fval)]))]
...))

I'm guessing the problem is in the  

[(FunV bound-id bound-body)
                (eval (subst bound-body
                       bound-id
                       arg-expr))]

部分。我尝试将其更改为

(eval (subst bound-body
                        bound-id
                        (Reg (RegV->bit-list(eval named-expr)))))

就像在With中一样，但是我在RegV->bit-list函数中遇到了错误。

我也试图使它成为：

[(FunV bound-id bound-body)
                    (eval (subst bound-body
                           bound-id
                           (eval (arg-expr)))]

但是再一次，eval必须获得regE，但可以看到arg-expr是RES类型。

所以我只是不知道该如何处理arg-expr部分。任何帮助都会得到帮助...

这是无法通过的测试之一：

    (test (run "{ reg-len = 3
 {with {x {0 0 1}}
 {with {f {fun {y} {and x y}}}
 {with {x {0 0 0}}
 {call f {1 1 1}}}}}}")
 => '(0 0 1))

错误：

RegV->bit-list: Given wrong type of RES (FunV y (And (Id x) (Id y)))

还有RegV->bit-list:

(: RegV->bit-list : RES -> Bit-List)
;; extract a bit-list from RES type
(define (RegV->bit-list r)
  (cases r
    [(RegV bl) bl]
    [else (error 'RegV->bit-list "Given wrong type of RES ~s" r)]
    )
  )

似乎问题始于with部分，但是代码在我添加“ fun”和“ call”部分以及所有旧测试通过之前运行良好，所以我猜它已经用call部分做某事...

DrRacket为ROL语言的eval函数添加“调用”

0 个答案: