jar398
commented
2 years ago So if I just type #t at a Common Lisp reader with the *roadblock-readtable* in effect, under your change, does that turn into the pseudoscheme true value? and similarly with other # syntaxes in scheme?
If so then I guess your fix is OK. If not it needs to be conditional on SBCL.
You probably know already that # is not a constituent character, but merely non-terminating (which is a sort of semi-constitutent status). (hyperspec) But for roadblock purposes the only thing that matters is its status as the first character of something, so making it a constituent with respect to the roadblock sounds wrong to me.
I am puzzled by the CCL changes - we're talking about Coral Common Lisp, right? Maybe CCL itself changed over the years. I never used it and must have gotten those conditionalizations from a contributor. Of course ideally all this knowledge of file extensions shouldn't reside inside Pseudoscheme itself. The underlying Lisp system obviously knows all of this and I'd expect there to be a way to query it in a modern Common Lisp. In retrospect the derived files should be foo-pso.lisp not foo.pso but remember - the file system I was using only supported 6 character file names.
Yes, this is very old code- I think mainly written around 1985, for the Symbolics Lisp Machine (which had only just implemented Common Lisp, which came out in 1984). It was never revised for ANSI Common Lisp or for ABCL. It's miraculous that it still works.
I believe the dialect implemented is R4RS, not R5RS.
Thanks for teaching me about 'draft' status PRs!
BenedictHW
Good Day,
I'm currently a beginner trying get started with Lisp. I've already invested hours setting up my ideal Emacs & Common Lisp environment with the copious free time only a student has. Therefore I began searching for a way to learn SICP through the Common Lisp environment. It was then Mr. Joswig on HN who pointed me towards pseudoscheme (https://news.ycombinator.com/item?id=16776704).
I decided to mark this Pull Request as a draft because I'm not entirely clear why removing '#' from the Non-constituents allows the readtable to be successfully set, and why this only occurs on SBCL. This is out of the two implementations I tested, the other being CCL. But seeing resources online as sparse as it is, I wanted to save future beginners some trouble by making this WIP PR public.
Loading pseudoscheme on SBCL v2.1.9 now does seem to work though. I ran some scheme examples I found online and pasted the results in the description of commit fba7323. I've also read online that it is most painless to use the version of scheme (R5RS?) in the textbook and not modern MIT Scheme or Racket (which can work with a compatibility module). So pseudoscheme seems to fit the bill perfectly. In fact I think some historical value would be lost if all the conditionals for ancient implementations were replaced. I think it's pretty cool code that is 16 years older than me remains a vehicle to learn the timeless concepts in SICP.
But now I've spent more time fooling around with the tooling instead of the material so I'll leave it at that.
Cheers, and thanks for pseudoscheme!