[racket] bracket conversion?

On Nov 20, 2012, at 3:53 PM, Robby Findler wrote:

> I think one way to do it would be to use read-syntax to get the
> expression, but then also put the file into a string. Walk the
> expression and look for patterns that you want to change rounds to
> squares and then mutate the string and write the file back out again.
> Use the position field of the syntax object to tell you where to
> mutate the string.

Yep, that's exactly what I was thinking.

> 
> You could even take a check-syntax like approach (it is more complex,
> tho) and fully expand the program. Then, when you find 'cond' in the
> origin field of some syntax object you can be sure it really is
> racket/base's cond and not some other thing like, eg
> 
> (lambda (cond) (cond 3 (+ 1 2)))

I think this would wind up being nearly impossible. I think the first one could be occasionally incorrect (e.g. someone re-binds the identifier 'new', and then what look like initialization clauses should be treated as applications), but that seems like a small price to pay for the massive simplification.

My guess: the whole thing would take about three days of work.

John


> 
> Robby
> 
> On Tue, Nov 20, 2012 at 5:09 PM, John Clements
> <clements at brinckerhoff.org> wrote:
>> 
>> On Nov 20, 2012, at 11:28 AM, Eric Tanter wrote:
>> 
>>> Thanks John, that's very helpful!
>>> 
>>> Any idea about a whole-file racketify in DrRacket?
>> 
>> That's a toughy. What you want is to be able to invert (read-syntax). It seems to me that such a thing should be possible in many of the racket languages, but I'm not aware of an implementation.
>> 
>> Actually, thinking about it harder, I suppose you have the original string text of the file, as well, so that makes it a hugely easier; you just need a predicate on the (un-expanded) syntax objects that can tell you whether a syntax list should have square or round brackets.
>> 
>> So, here's the $64K question: can you specify precisely which places need to be changed? If so, it sounds like this is do-able.
>> 
>> John
>> 
>> 
>> 
>>> 
>>> -- Éric
>>> 
>>> 
>>> On Nov 20, 2012, at 3:16 PM, John Clements wrote:
>>> 
>>>> 
>>>> On Nov 20, 2012, at 10:01 AM, Eric Tanter wrote:
>>>> 
>>>>> Hi,
>>>>> 
>>>>> I'm converting code written with only standard parentheses, introducing squared ones where appropriate.
>>>>> 
>>>>> This is obviously not very fun (I'm converting all of OOPLAI), and it would be great if there'd be a way to select an open paren and "convert" it so that the matching closing paren is changed automatically.
>>>>> 
>>>>> Is this feasible?
>>>>> 
>>>> 
>>>> I'm pretty sure Sam and I added this binding last year. C-c C-[ ? I think you can look it up in the keybindings.
>>>>> 
>>>> 
>>>> John
>>>> 
>>> 
>> 
>> 
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