2017-04-26から1日間の記事一覧

SICPゼミ第45回

練習問題4.16 (define (lookup-variable-value var env) (define (env-loop env) (define (scan vars vals) (cond (( null? vars) (env-loop (enclosing-environment env ))) ((eq? var (car vars )) (if (eq? (car vals) '*unassigned*) (error "Unassigned…