To be fair, trace is more than that. Vincent's solution does work, but you have to modify the file - you can't do this from the REPL. You can modify the file containing the identifier you want to trace, if changing call sites is not palatable to you. Add `(require racket/trace)` at the top, and after the function definition `(trace function)`. Alternatively, if you only want to trace at given points in time, define and provide a function `(define (add-trace) (trace function))` so you can call `add-trace` when you want to turn on tracing.
A missing feature for racket/trace is to provide a setter function so that modules that export a mutating function can be traced without depending on racket/trace. If a module contains a `set!` for an identifier, it disables any inlining for that identifier. e.g. (trace #:setter set-function!) -Ian ----- Original Message ----- From: "Thomas Lynch" <thomas.ly...@reasoningtechnology.com> To: "J. Ian Johnson" <i...@ccs.neu.edu> Cc: "users" <users@racket-lang.org> Sent: Monday, January 19, 2015 9:49:51 AM Subject: Re: [racket] trace: set!: cannot mutate module-required identifier - alright .. how do you do this? So to trace calls to the interface functions of a library I am to write a gasket for the library. I may as well put a display of the args in the gasket functions as at this point it is the same amount of code as hooking the trace. Of course then I have implemented trace. So to use trace in racket all you have to do is implement trace .. really?? On Mon, Jan 19, 2015 at 10:06 PM, J. Ian Johnson <i...@ccs.neu.edu> wrote: > Yes, racket 101 (305?) is that identifiers can only be set!'d in their > defining module. This is to allow necessary optimizations such as inlining. > > If you want to trace `f` from a different module. you can `(define (g . > args) (apply f args)) (trace g)`, use `g` wherever you use `f`. You won't > get any calls the library makes internally, but if you're just tracing for > your own code, you'll be golden. > > -Ian > > ----- Original Message ----- > From: "Thomas Lynch" <thomas.ly...@reasoningtechnology.com> > To: "users" <users@racket-lang.org> > Sent: Monday, January 19, 2015 8:59:55 AM > Subject: [racket] trace: set!: cannot mutate module-required identifier - > alright .. how do you do this? > > Saw this in another thread here, but the proposed solution didnt work, > well at least the way I understood it. So .. > > In file db-lib.rkt I have a definition: > > > > > (provide db-exec) > (define (db-exec a) ...) > > Then in racket > > > > > > (enter! "db-user.rkt") > > Where db-citation.rkt has > > > > > (require "db-lib.rkt") > > Now at the read-eval-print prompt I try > > > > > (enter! "db-citation.rkt") > > And when I do (trace db-exec) I get the cannot mutate error. (Surely this > must be a racket 101 type problem.) So I try to include the module at the > current scope.. > > > > > rac...@db-citation.rkt> (require "db-lib.rkt") > rac...@db-citation.rkt> (require racket/trace) > rac...@db-citation.rkt> (trace db-exec) > > rac...@db-citation.rkt> stdin::1130: set!: cannot mutate module-required > identifier in: db-exec > ok, so that doesn't work, so I start over again. This time after reading > the thread on this list > > > > > From: Vincent St-Amour (stamourv at ccs.neu.edu ) > Date: Mon Oct 10 13:49:46 EDT 2011 > > which concludes by saying 'put the trace in your program that should > work', so I add this to "db-citation.rkt" > > > > > (require racket/trace) > (trace db-exec) > > And then at the prompt I get the following: > > > > > Welcome to Racket v5.2.1. > racket@> (enter! "db-citation.rkt") > db-citation.rkt:26:11: set!: cannot mutate module-required identifier in: > db-exec > > Alright, so what is the magic incantation here that allows one to > debug/trace calls in included modules? > > Thanks! > > Thomas > > ____________________ > Racket Users list: > http://lists.racket-lang.org/users > ____________________ Racket Users list: http://lists.racket-lang.org/users
