> maximum line length for entering J sentences into the interpreter?
For immex, 1024 bytes. This includes the leading 3 spaces (if present) but not
the trailing line terminator (I'm not sure line terminators are ever actually
in the buffer after you you press enter in immex).
For scripts, I haven't hit a limit.
> I can't seem to easily find this in the documentation:
It's not in there. I found the immex limit the hard way:
http://www.jsoftware.com/pipermail/general/2002-June/009131.html
Well, actually, that was a long time ago. Maybe it's changed since then?
NB. Ensure that long lines are at least
NB. displayed to their full precision,
NB. to eliminate truncation as a source
NB. of error.
9!:37 ] 0 _ 0 _
NB. Create a long line of executable J.
'x',~1023#'9'
999999999999999999...x
NB. Put cursor on long line, press enter twice
999999999999999999...x
999999999999999999...
NB. Everything is fine
NB. Note that 1023 nines + a trailing x
NB. is 1024 bytes (assuming ASCII).
>./#;._2 wd'sminputlog'
1024
NB. Now try bumping it above 1024
'x',~1024#'9'
999999999999999999...x
NB. Again, put cursor on long line, press enter twice
999999999999999999...x
_
NB. The result is _ because the trailing x was truncated,
NB. so the number wasn't interepreted as an extended integer.
NB. Our suspicions confirmed: 1024 nines + trailing x
NB. is 1025 bytes, but the input log still only
NB. reports a max of 1024. The last char (the x)
NB. never made it to the engine. Immex must've
NB. truncated it.
>./#;._2 wd'sminputlog'
1024
NB. Now, to make J crash, press CTRL+SHIFT+UP twice or
NB. put cursor on last long line and press CTRL+R
Of course, if you're typing 1024-byte long lines into immex, you have bigger
problems than truncation (or maybe you're using Unicode ;). I just happened to
find this bug while attempting to debug a script line by line with CTRL+R.
Oh, on that point: I'll reiterate that this is only a limitation if immex
(i.e. the IJX window). I have not encountered such a limit in scripts (i.e.
IJS windows, or arguments to 0!: ). Though, amusingly, while writing up this
post, I found a limit on immex *output*: even though I set 9!:37 ] 0 _ 0 _ ,
output lines are still truncated (to 3067 bytes, it seems).
-Dan
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