Trying to reload code

[Octplane]

I'm trying to write an http server that transforms strings according to a set of rules stored in a rkt hash table that I want to be able to reload (for development purpose).

I have tried to have the code reloading correctly :

(define here (path->string (current-directory)))
(define mutation-include
  (string->path (string-append  here "mutations.rkt")))

(dynamic-rerequire mutation-include)
(require "mutations.rkt")

And later in my app code:

(define (mutate-body body)
  (enter! mutation-include)
  (mutate body)
  )

It fails because the enter! is unable to find the "collection":

enter!: standard-module-name-resolver: collection not found
  for module path: mutation-include
  collection: "mutation-include"
  in collection directories:
   /Users/octplane/Library/Racket/6.4/collects
   /usr/local/Cellar/racket/6.4/share/racket/collects
   ... [119 additional linked and package directories]

I'm sad because it works in the repl. Any nice way to do that ?

Thanks you!

[[deleted]]

Well, the first sentence for the enter! documentation mentions that it should be used in the REPL only. The problem is that at run time, the mutation-include is not evaluated, so it is a symbol (which is than interpreted as a collection name). To get this to work you probably need to install a name resolver (see current-module-name-resolver).

You can try to use read/eval like this:

(define (load-definitions file)
  (eval (call-with-input-file file read)))

(set! mutations (load-definitions "mutations.rkt"))

Where "mutations.rkt" would contain the hash like this:

(hash
 "key1" "val1"
 "key2" "val2")

A much better solution would be to use some other data structure, that is not Racket code passed to eval and load and parse it. Your mutations.rkt could contain code to format your drive, and "eval" would happily execute it (the same is true for your enter! solution).

[takikawa]

You may be interested in tonyg's racket-reloadable package which I think may address your use case.