environment.lsp

(define map (lambda (func list)    (cond (        ((eq? list '()) '())        (#t (cons (func (car list)) (map func (cdr list))))    ))))
(define foldl (lambda (binfunc acc list)    (cond (        ((eq? list '()) acc)        (#t (foldl binfunc (binfunc (car list) acc) (cdr list)))    ))))
(define foldr (lambda (binfunc acc list)    (cond (        ((eq? list '()) acc)        (#t (binfunc (car list) (foldr binfunc acc (cdr list))))    ))))
(define filter (lambda (pred list)    (cond (        ((eq? list '()) '())        ((pred (car list)) (cons (car list) (filter pred (cdr list))))        (#t (filter pred (cdr list)))    ))))
(define length (lambda (l) (foldl (lambda (first acc) (+ 1 acc)) 0 l)))
(define reverse (lambda (l) (foldl cons '() l)))
(define append (lambda (l1 l2) (foldr cons l2 l1)))
(define list (lambda (. items) (foldl cons '() items)))
(define list? (lambda (input)    (cond (        ((atom? input) #f)        ((eq? input '()) #t)        (#t (list? (cdr input)))    ))))
(define abs (lambda (x) (if (> x 0) x (neg x))))
(define modulo (lambda (x m) (- x (* (/ x m) m))))
(define list->string (lambda (list)    (foldl (lambda (first acc) (string-append (make-string 1 first) acc)) "" (reverse list))))
(define string->list (lambda (str)    (cond (        ((eq? str "") '())        (#t (cons (string-ref str 0) (string->list (substring str 1 (string-length str)))))    ))))
(define apply (lambda (op . list) (foldl op (car list) (cdr list))))
(define if (macro (test if_clause else_clause)    (cond ((test if_clause) (#t else_clause)))))
(define let (macro (bindings expression)   (begin       (define new_env (foldr cons (current-environment) (quote bindings)))       (eval expression new_env)   )))