Hacker Newsnew | past | comments | ask | show | jobs | submitlogin

You know, after some testing with a bunch of different scheme implementations, I take back what I said, at least for working in a REPL.

    (define (displayln msg) (display msg) (newline))
    (define (inner x) (+ x 1))
    (define (outer x) (inner x))
    (displayln (outer 5))
    (define (inner x) (+ x 2))
    (displayln (outer 5))
outputs 6 and 7 in every one I tried, not the 6 and 6 I expected.


Perhaps you were thinking of lexical scope vs dynamic scope? Lexical scoping would prevent a local definition of inner from changing the definition used in outer.

  (let ((inner (lambda (x) (+ x 3)))) (outer 5))
  "7"
But updating the definition of inner with set! or define changes the top-level definition.


Yes, I was thinking of lexical scope; as in redefining the function shadows the existing one and doesn't change the function already defined uses of call.




Guidelines | FAQ | Lists | API | Security | Legal | Apply to YC | Contact

Search: