Itty Bitty Programming Language Assignment

Credit

This assignment is based on MUPL by Dan Grossman and his team at UW.

Code To Use

• raise-argument-error
• exact-integer?
• cons?
• null?
• cons
• car
• cdr

Code To Investigate

Ast

Expression Structs

(struct IdentifierExp (name)                                           #:transparent)
(struct IntExp        (value)                                          #:transparent)
(struct AddExp        (left_exp right_exp)                             #:transparent)
(struct IfGreaterExp  (left_exp right_exp then_body_exp else_body_exp) #:transparent)
(struct NilExp        ()                                               #:transparent)
(struct IsNilExp      (exp)                                            #:transparent)
(struct ConsExp       (car_exp cdr_exp)                                #:transparent)
(struct CarOfConsExp  (cons_exp)                                       #:transparent)
(struct CdrOfConsExp  (cons_exp)                                       #:transparent)
(struct LetExp        (binding_name binding_exp body_exp)              #:transparent)
(struct FunctionExp   (name_option parameter_name body_exp)            #:transparent)
(struct CallExp       (function_exp argument_exp)                      #:transparent)

expression?

(define (expression? exp)
  (or (IdentifierExp? exp)
      (IntExp? exp)
      (AddExp? exp)
      (IfGreaterExp? exp)
      (NilExp? exp)
      (IsNilExp? exp)
      (ConsExp? exp)
      (CarOfConsExp? exp)
      (CdrOfConsExp? exp)
      (LetExp? exp)
      (FunctionExp? exp)
      (CallExp? exp)))

Code To Implement

Warmup

file:	src/main/racket/ibpl/warmup.rkt
functions:	racket-integers->ibpl-IntExps ibpl-IntExps->racket-integers

Interpreter

file:	src/main/racket/ibpl/interpreter.rkt
functions:	value? expand-environment evaluate

(struct closure (env function) #:transparent)

value?

IBPL expressions evaluate to Racket values. value? determines if the paramater v is a valid value.

Valid value types are cons cells, integers, closures, and the null empty list.

For a cons cell to be a valid value, its car and cdr must be valid values.

ensure-value?

(define (ensure-value? v)
  (if (value? v)
      v
      (raise-argument-error 'v "value?" v)))

lookup-value-in-environment

(struct entry (name value) #:transparent)

(define (lookup-value-in-environment env identifier-name)
  (cond [(null? env) (error "unbound identifier during evaluation" identifier-name)]
        [(equal? (entry-name (car env)) identifier-name) (entry-value (car env))]
        [#t (lookup-value-in-environment (cdr env) identifier-name)]))

expand-environment

(define (expand-environment name value env)
        (error 'not-yet-implemented))

Requirement: raise-argument-error for invalid parameters.

evaluate

(define (evaluate exp env)
  (if (expression? exp)
      (if (list? env)
          (ensure-value? 
                 (error 'not-yet-implemented))
          (raise-argument-error 'env "list?" env))
      (raise-argument-error 'exp "expression?" exp)))

Macros

IbLet*

(struct binding (name exp) #:transparent)

Testing

file:	test_all.rkt	Test
source folder:	src/test/racket/ibpl

note: ensure that you have removed all printing to receive credit for any assignment.