#lang typed/racket

(provide Cell
         Tape
         Instruction
         Token
         Program
         Loop)

(define-type Cell (U Zero Positive-Byte))

(define-type Tape (Listof Cell))

(define-type Instruction
  (U 'pointer-increment
     'pointer-decrement
     'increment
     'decrement
     'output
     'input
     Loop))

(define-type Token
  (U 'pointer-increment
     'pointer-decrement
     'increment
     'decrement
     'output
     'input
     'loop-start
     'loop-end))

(define-type Program (Listof Instruction))

(define-type Loop Program)