defunctionalize NbE

defunctionalize-nbe.scm

;; http://www.brics.dk/RS/01/23/BRICS-RS-01-23.pdf

(define (eval term env)
  (match term
    ((symbol? s) (lookup s env))
    (`(lambda (,(symbol? v)) ,body) (lambda (x) (eval body (cons (cons v x) env))))
    (`(,m ,n) ((eval m env) (eval n env)))))

;; Defunctionalize ==>

(define (apply l x)
  (match l
    (`(closure ,body ,v ,env) (eval body (cons (cons v x) env)))))

(define (eval term env)
  (match term
    ((symbol? s) (lookup s env))
    (`(lambda (,(symbol? v)) ,body) `(closure ,body ,v ,env))
    (`(,m ,n) (apply (eval m env) (eval n env)))))