#lang typed/racket

(define-type ConId Integer)
(define-type Arity Integer)
(define-type Let (∪ 'let 'letrec))
(define-type Name Symbol)


(define-type (Bind A) (List A (Expr A)))
(define-type (Alt A) (List 'branch ConId (Listof A) (Expr A)))

(define-type (Expr A)
  (∪ Name
     Integer
     (List 'pack ConId Arity)
     (List (Expr A) (Expr A))
     (List Let (Pair (Bind A) (Listof (Bind A))) (Expr A))
     (List 'case (Expr A) (Pair (Alt A) (Listof (Alt A))))
     (List 'λ (Pair Name (Listof Name)) (Expr A))))