Interesting. I had never heard of 3d syntax before. But I'm not sure what
advantage 3d syntax would get me here. If I have to write my own custom
version of "define", couldn't it just as easily detect a dot in a regular
syntax object?
On Wednesday, December 19, 2018 at 6:29:22 PM UTC-6, Milo
Another option, which probably has a lot of terrible consequences, is to
transform "a.b" into "3-d syntax" (a struct embedded in syntax) that can
now be interpreted differently by forms that are interested. For instance a
custom "define" could grab the 3d-syntax in the name and use it to make a
Thanks for your response Alexis. You are right: once I figured out the
correct way to customize the reader, the rest fell into place much more
easily. Now, when my reader sees a dot it asks the base reader to read
another piece of syntax, which must be an identifier.
So (define a.b 3) becomes
I think your initial instinct was right: if you want to change the lexical
structure of your language, the right place to start is in the reader. The
reader is the part of Racket’s language facilities that interprets the
structure of sequences of characters, and your notion of dotted
It turns out expanding the syntax object isn't the right approach. It seems
easy enough for defining values and simple procedures, but as soon as you
consider optional arguments and keyword arguments, the resulting expansion
gets too complicated to analyze.
I don't see an easy way to do this,
Thanks Matthew, I think I can adapt that approach. As written, it's not
quite what I had in mind because it disallows foo.bar in an expression
context, before I get a chance to transform it to (bar foo). So I am going
to try to (expand #'(module a racket . EXPRS)) and then search the
> On Dec 9, 2018, at 8:20 PM, default.kra...@gmail.com wrote:
> Is there an easy way to disallow certain characters in identifiers? I
> realized it's not just dots I want to disallow, but also operators like +
> which might be interpreted as infix in certain contexts.
Roughly, I imagine you'd
I am trying to make a language based on Racket in which a.b would not be
allowed as an identifier, rather it would expand to something like (b a).
Seems like a job for read-cdot, right? Well I quickly learned it's not that
simple. With read-cdot on (define a.b 3) is not an error, rather it
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