problem-1.rkt

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;;; part 1
;;; do not modify anything in this file except for interp and type-check?. You
;;; are permitted to add your own helper functions, structs, etc.

#lang racket
(require rackunit)

(define (eveclang? e)
  (or (elet? e) (evec? e) (egetvec? e) (enum? e) (eident? e)))

;;; do not change these structs
(struct elet (id assgn body) #:transparent
  #:guard (struct-guard/c string? eveclang? eveclang?))
(struct eident (id) #:transparent
  #:guard (struct-guard/c string?))
(struct evec (l) #:transparent
  #:guard (struct-guard/c (listof integer?)))
(struct enum (n) #:transparent
  #:guard (struct-guard/c integer?))
(struct egetvec (e idx) #:transparent
  #:guard (struct-guard/c eveclang? integer?))

;;; declare a type exception that is a subtype of exn:fail
(struct exn:type exn:fail ())
(define (raise-type-error)
  (raise (exn:type
          "type error"
          (current-continuation-marks))))

(define (interp e)
  (error 'implementme))

(define (type-check? e)
  (error 'implementme))

(define example-term
  (elet "x" (evec (list 1 2 3))
        (egetvec (eident "x") 1)))

(define example-term-2
  (elet "x" (evec (list 1 2 3))
        (egetvec (eident "x") 10)))