Evaluating Medley compatibility with Practical Common Lisp code: Chapters 30 and 31

[pamoroso]

Chapters 30 and 31

This is the continuation of the work on issue #609. To evaluate the compatibility of Medley Common Lisp with ANSI Common Lisp I'm testing on Medley the code of Peter Seibel's book Practical Common Lisp.

Code

Chapters 30 and 31 describe an HTML generation library.

Since this is a more substantial project than those in earlier chapters I'm preparing to test the code in two steps. First, from Medley I manually load in the proper order the source files that come with the book. These files depend from a macro library described in chapter 8 which I also load.

Once I manage to load the files correctly I will evaluated at a XCL Exec the example expressions of the chapter, with the addition of just a couple of missing calls.

The source files require the following modifications to the package definition and access code:

• substituting strings for keywords as package designators and exported symbols (otherwise I get occasional errors I'm trying to reproduce)
• commenting out the definition of with-gensyms which XCL already has
• replacing the :use lists of package definitions to include LISP, XCL, and CLOS (because system packages are slightly different on Medley; and because I'm using the Medley Online 19-Mar-2024 02:06:49 build in which some packages are partially broken as a side effect of the initial port of Sacla LOOP, so CLOS is required to avoid errors such as Undefined car of form DEFCLASS)

Here are the source files, renamed from .lisp to .txt as GitHub requires:

• pclchap8-packages.txt
• pclchap8.txt
• pclchap31-packages.txt
• pclchap31-html.txt

File loading issue

I hit a snag with this setup as I'm unable to proceed due to a file loading issue. From a XCL Exec I load the source files in this order:

1. pclchap8-packages.lisp
2. pclchap8.lisp
3. pclchap31-packages.lisp
4. pclchap31-html.lisp

As soon as I load pclchap31-html.lisp I'm immediately logged out of Medley Online and the session ends.

[pamoroso]

Since loading pclchap31-html.lisp causes the termination of the Medley Online session, I used the bisection method to narrow down where the issue occurs. Instead of loading pclchap31-html.lisp after the files it depends on, I proceeded by loading a modified copy of pclchap31-html.lisp containing the code up to a line indicated by the bisection method.

The result is the issue lies between lines 316 and 320 (inclusive) of pclchap31-html.lisp. That portion of the file contains only this code:

(defun parse-cons-form (sexp)
  (if (consp (first sexp))
    (parse-explicit-attributes-sexp sexp)
    (parse-implicit-attributes-sexp sexp)))

Nothing jumps at me but that code might just trigger an issue located elsehere.

[masinter]

pclchap8-31.zip

i got further with some problems I suspect in CLOS. The crash is a stack overflow that needs more than the stack reserve tobreak and needs RAID to hard reset, but isn't readily availabe online. I suspect CLOS because the recursion involved IL:\INTERPRETER, IL:\REMOVE-DECLS etc.
try compiling first and then loading the compiled files. see attached zip.

[pamoroso]

Now I can load the compiled files correctly. But when I evaluate test expressions I get undefined function errors like this:

2/12> (in-package :com.gigamonkeys.html)
#<Package COM.GIGAMONKEYS.HTML>
2/13> 

2/13> *package*
#<Package COM.GIGAMONKEYS.HTML>
2/14> (apropos "PROCESS-SEXP-HTML")
PROCESS-SEXP-HTML
2/15> (html (:p "foo"))
In IL:OLDFAULT1:
PROCESS-SEXP-HTML is an undefined function.

2/16: ^

2/17>

process-sexp-html is defined in pclchap31-html.lisp and is internal to package com.gigamonkeys.html, but in-package should take care of that.

[pamoroso]

Never mind, the code of these chapters includes several calls to write-sequence which Medley Common Lisp doesn't support.