code from the afternoon class, 2018-10-03

2018-10-03-afternoon.rkt

#lang typed/racket

(require typed/rackunit)


(define-type Value String)

(define-type ExprC (U ConcatC StrC))
(struct ConcatC ([l : ExprC] [r : ExprC])
  #:transparent)
(struct StrC ([s : String]) #:transparent)

(ConcatC (StrC "abc") (StrC "def"))

#;((check-equal? (interp (parse '"apple")) "apple")
(check-equal? (interp (parse '{"abc" + "def"}))
              "abcdef"))