Hi Steve,
On Tue, 17 Mar 2015 22:27:38 +0000 (UTC), Steve Graham
Post by Steve GrahamGeorge,
Your unicode comment made me wonder. So I wrote out some code to
the repl and it "compiled" and ran fine. Next I copied that code to
Notepad and then copied and pasted it back to the repl and it "compiled"
and ran fine. Finally I google "scheme factorial" and copied what I
found to the repl and there I had problems.
I have seen a few editions of DrRacket [including 6.1.1 release] hang
or crash loading a source file that has an embedded UTF BOM header.
CLI racket or raco will complain about the module language being
unknown or not found [can't remember the exact message], so if the
file otherwise looks correct, that is a quick test for the header
being present.
If DrRacket does manage to load the file, you'll see a couple of weird
glyphs (that can't be removed!) at the beginning.
Only solution is to use another editor to remove the header. May be
just my luck, but I haven't yet found an editor that will remove an
existing BOM header just by saving to a different format. I use the
hex/bin function of my code editor to manually remove the header
bytes.
The compiler - at least in conjunction with DrRacket - also doesn't
much like multi-byte characters. As you have discovered, sometimes
things which visually appear to be correct just won't compile.
My solution, if that happens, is to load the file in a different
editor, resave it as Western (ISO-8859-1) to quickly clean up as much
as possible and then retype in DrRacket any lines that still produce
syntax errors.
I have never investigated whether the compile problem is only in
conjunction with the Dr editor or is pervasive. I generally do a lot
of testing/tweaking in the debug environment before moving to CLI
racket. By that time I no longer have the compile problem.
Unfortunately, I don't encounter either unicode problem very often,
and when I do it tends to be when I'm really busy, so I just deal with
it and forget about bug reports. Yeah, I know. Selfish 8-(
Post by Steve Graham: First saw this in the arc programming language, which is based
on Racket.
The funny thing is that a number of other Scheme implementations do
not act thusly. I wonder what can be done to remove this from Racket.
If you have an example that fails reliably, you should file a bug
report.
George
Post by Steve Graham---
;; Typed into repl
(define (fact n)
(if (< n 2)
1
(* n (fact (- n 1)))))
(fact 5)
120
;; Copied from Notepad into repl> (define (fact n)
(if (< n 2)
1
(* n (fact (- n 1)))))
(fact 5)
120
;; Copied from browser into repl> (define (factorial n)
(if (= n 0)
1
(* n (factorial (- n 1)))))
stdin::355: if: bad syntax;
has 4 parts after keyword
in: (if (= n 0) 1 R (* n (factorial (- n 1))))
C:\Program Files\Racket\collects\racket\private\misc.rkt:87:7
Sent: Tuesday, March 17, 2015 2:21 PM
Subject: Re: [racket] Error when pasting code
On Tue, 17 Mar 2015 19:06:50 +0000 (UTC), Steve Graham
When running the following code, when manually typed in, there is no
error. However, when the same is pasted from the keyboard buffer,
the error indicated appears.
Comments?
Thanks, Steve
Likely there are hidden control characters being carried when you cut
and paste.
I've had troubles going back and forth between DrRacket and various
unicode aware code editors - everything from syntax errors compiling
to DrRacket hanging or even crashing trying to load source files.
Inevitably it is because some hidden character(s) snuck in.
I haven't actually experienced it with cut-n-paste, but it would not
surprise me.
George
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