I have an alpha-test version of a syntax checker for J scripts. It is
in the addons, as
general/misc/lint.ijs
The goal is to catch errors before execution. It can find only gross
errors, but those are the kind my programming students make, so this is
progress IMO. What it looks for is:
explicit definitions lacking trailing ), and ) with no definition
undefined names, including names not defined in all paths
verbs used with invalid valences
non-noun results at the end of condition blocks and verbs
syntax errors
sentences with no effect on execution (eg verb verb)
The idea is that lint can be used in place of load. It loads the
script, then checks it for errors by executing each line of each
explicit definition in 'safe mode' where side effects are prevented.
example:
lint '~addons/general/misc/lint.ijs'
The result of the verb is a table of (line number);(error message).
If there are errors, it brings up a grid showing the program and error
messages.
I would test this a lot more before releasing it, but school starts
tomorrow & I'm not going to have much more time to put on it. I think
it's better than nothing - not freshman-proof, but I'll fix that as the
freshmen tear into it. Meanwhile I would appreciate suggestions and bug
reports.
(My thanks to Dan King who suggested this project at the J Conference in
response to my bellyaching about J's error-detection deficiencies)
Henry Rich
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