In the Racket version 7.0 on Windows, a contract violation error in an
executable program will trigger a very confusing error message. I think
this
is best illustrated by an example. Consider the file:
#lang racket
(require racket/contract)
(define/contract (foo n)
(-> integer? any/c)
(printf "foo: ~a~%" n))
(module+ main
(foo "hello"))
When run from the command line, this program will report a contract
violation,
correctly indicating the problem:
$ racket c.rkt
foo: contract violation
expected: integer?
given: "hello"
in: the 1st argument of
(-> integer? any/c)
contract from: (function foo)
blaming: e:\Alex\t\c.rkt
(assuming the contract is correct)
at: e:\Alex\t\c.rkt:4.18
If I compile and make a distribution from this program using `raco exe`
followed by `raco dist`, than try to run the resulting executable I get:
$ raco exe c.rkt
$ raco dist c-dist c.exe
$ ./c-dist/c.exe
build-path: contract violation
expected: (or/c path-for-some-system? path-string? 'up 'same)
given: #f
argument position: 1st
other arguments...:
"pkgs"
Is there a way to improve this error message? I sort of understand why the
program not be able to report the full contract and line number, but it
should
at least say something along the lines of "a contract violation has
occurred,
no further detail available", instead of reporting the `build-path` contract
violation.
Thanks,
Alex.
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