lisp - symbolic expression stream I/O -


in common lisp, how can 1 read & write symbolic expressions from/to streams? example, might want write anonymous function file , read , funcall it:

;;; sexp-io.lisp ;;; try writing sexp file , reading in  (with-open-file (file "~/documents/lisp/concurrency/sexp.lisp"                   :direction :output :if-exists :supersede)   (print #'(lambda () (+ 1 1)) file))  (with-open-file (file "~/documents/lisp/concurrency/sexp.lisp"                   :direction :input)   (read file))

however, code results in dubious output

 #<anonymous function #x3020018f950f>

which result in error when try reading in:

> error: reader error on #<basic-file-character-input-stream ("/users/frank/documents/lisp/concurrency/sexp.lisp"/7 utf-8) #x3020018f559d>, near position 3, within " >        #<anonymous ": >        "#<" encountered. > while executing: ccl::signal-reader-error, in process listener(4).

you doing trt, except #' turns list (lambda () (+ 1 1)) function object. replace sharp-quote (which read function) simple quote (which read quote) , should work.

another change might want make replacing print write argument :readably t:

(write my-object :stream out :readably t)

the benefit of :readably fails if cannot write in way preserve print-read consistency.


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