SERIES の encapsulated

Common Lisp の SERIES with-open-file 等の unwind-protect を使う場合はencapsulated を使うといいらしい？

encapsulated の第二引数で使えるのは SCAN-FN, SCAN-FN-INCLUSIVE, COLLECT-FNのいずれか。

よくわかってない。。。詳細は SERIES に添付の s-doc.txt を参照。

(require :series)
(use-package :series)

(defun scan-file-wrap (file name body)
  `(with-open-file (,file ,name :direction :input) ,body))

(defmacro simple-scan-file (name)
  (let ((file (gensym)))
    `(encapsulated #'(lambda (body)
                       (scan-file-wrap ',file ',name body))
                   (scan-fn t
                            (lambda ()
                              (read ,file nil))
                            (lambda (x)
                              (read ,file nil))
                            #'null))))

(let ((x (simple-scan-file "/tmp/b.txt")))
  (collect-sum (map-fn t (lambda (x) (* x x)) x)))