debug

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Some trivial debugging macros

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debug
- Abstract
- Documentation
- About this egg
  - Author
  - Repository
  - License
  - Dependencies
  - Versions
  - Colophon

Abstract

According to Joe Armstrong, "The great gods of programming said, 'Thou shalt put printf statements in your program at the point where you think it’s gone wrong, recompile, and run it.'"

Documentation

debug?

debug?parameter

`debug?' turns on or off debugging output, depending on whether it is set to #t or #f; respectively.

(define debug? (make-parameter #t))

trace

(trace f) → unspecifiedsyntax

Trace the input to and output from a function.

f: The function to be traced

(define-syntax
  trace
  (er-macro-transformer
    (lambda (expression rename compare)
      (match-let
        (((_ f) expression))
        (let ((%set! (rename 'set!))
              (%lambda (rename 'lambda))
              (%call-with-values (rename 'call-with-values))
              (%apply (rename 'apply))
              (%format (rename 'format))
              (%values (rename 'values))
              (%let (rename 'let))
              (%f (rename 'f))
              (%when (rename 'when))
              (%debug? (rename 'debug?)))
          `(,%when
            (,%debug?)
            (,%let
             ((,%f ,f))
             (,%set!
              ,f
              (,%lambda
               x
               (,%format (current-error-port) ";; Arguments to ~a: ~a~%" ',f x)
               (,%let
                ((return-values
                   (,%call-with-values
                    (,%lambda () (,%apply ,%f x))
                    (,%lambda x x))))
                (,%format
                 (current-error-port)
                 ";; Values from ~a: ~a~%"
                 ',f
                 return-values)
                (,%apply ,%values return-values)))))))))))

debug

(debug expressions) → unspecifiedsyntax

Debug the expressions to stderr by pretty-printing each expression and their evaluations.

expressions: The expressions to be debugged

(define-syntax
  debug
  (syntax-rules
    ()
    ((_ x ...)
     (with-output-to-port
       (current-error-port)
       (lambda ()
         (when (debug?)
               (pp `(,(if (or (boolean? 'x)
                              (char? 'x)
                              (number? 'x)
                              (string? 'x)
                              (vector? 'x))
                        x
                        `(x =>
                            ,(handle-exceptions
                               exn
                               (let ((message
                                       ((condition-property-accessor 'exn 'message) exn))
                                     (arguments
                                       ((condition-property-accessor 'exn 'arguments)
                                        exn)))
                                 (format
                                   "Error: ~a~a"
                                   message
                                   (if (null? arguments)
                                     ""
                                     (format
                                       ": ~a"
                                       (string-join (map ->string arguments) ", ")))))
                               x)))
                     ...))))))))

debug-priority

debug-priorityparameter

The priority associated with debug/syslog

(define debug-priority (make-parameter prio/debug))

debug/syslog

(debug/syslog expressions) → unspecifiedsyntax

Debug to syslog.

expressions: The expressions to debug (cf. `debug' supra)

(define-syntax
  debug/syslog
  (ir-macro-transformer
    (lambda (expression rename inject)
      `(let ((port (make-syslog-port)))
         (with-error-output-to-port
           port
           (lambda ()
             (when (debug?)
                   (debug ,@(cdr expression))
                   (flush-output port))))))))