Den søn. 7. jun. 2020 kl. 14.09 skrev Siyuan Chen <[email protected]>:
Unfortunately, this code doesn't work, because it lacks two functions, > `get-current-env` and `extends-env`. > These are not available since static lexical scope makes it possible for the compiler to determine where a variable is stored at compile time. Therefore an explicit environment is not needed. (See "early binding" vs "late binding"). > Is there any way to work around this issue? > > I have searched Racket's document. Racket has namespaces that are very > similar to the environment here. > > But it seems that `current-namespace` can not get binding (e.g. Just) and > `namespace-set-variable-value!` is a mutable function which is not suitable > as well. > Namespaces are "environment-like" but contain only top-level variables. Could someone give me some advice? > Or we can modify the code above to make it work in Racket. > Since this for educational/fun use and not practical, I suggest using a Scheme interpreter where the environments are explicit. Then you can easily add `get-current-env` and `extends-env` yourself. One option is the interpreter page LiSP (Lisp in Small Pieces) where an interpreter for fexprs is discussed with full working code. /Jens Axel https://racket-stories.com -- You received this message because you are subscribed to the Google Groups "Racket Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/racket-users/CABefVgwBO%2BMG6SH66mHM_-LTsxpWTBsTu-%3DKSQ-skwjmUQvBOA%40mail.gmail.com.
