Make racket/trace output go to a logger

trace.log-rkt

#lang racket/base

(require racket/format
         racket/list
         racket/match
         racket/trace)

(provide (all-defined-out)
         (all-from-out racket/trace))

;; 1. `require` this. Now racket/trace will output using
;; log-trace-debug.
;;
;; 2. Add `(trace func1 func2 ...)` at the bottom of your file.
;;
;; 3. In racket-mode or DrRacket, set the logger to show 'debug level
;; for the "trace" logger (a.k.a. topic).

(define-logger trace)

(define (trace-notify s)
  (log-trace-debug "~a" s))

(define top-left #\u250c)
(define bot-left #\u2514)
(define horz     #\u2500)
(define vert     #\u2502)
(define rarrow   #\u25b6)

(define (trace-print-args name args kws kw-vals level)
  (printf
   "~a~a~s\n" ;add \n because it will be stripped for trace-notify
   (make-string level vert)
   top-left
   `(,name ,@args ,@(append-map list kws kw-vals))))

(define (trace-print-results name results level)
  (printf
   "~a~a~a~a~a\n" ;add \n because it will be stripped for trace-notify
   (make-string level vert)
   bot-left
   horz
   rarrow
   (match results
     [(list)   "** no values **"]
     [(list v) (~v v)]
     [vs       (~v (cons 'values vs))])))

(current-trace-notify trace-notify)
(current-trace-print-args trace-print-args)
(current-trace-print-results trace-print-results)

(module+ test
  (define (f x) (if (zero? x) 0 (add1 (f (sub1 x)))))
  (trace f)
  (f 3)
  (define (g x) (values (f x) (add1 x)))
  (trace g)
  (g 5))