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This took me three months (a month longer than I had hoped), but I finally have merged it into the main branch!

This patch rewrites the Emacs Lisp lexer and parser in Scheme using Scheme code that is 100% compliant with the #R7RS standard, so it should now work across all compliant Scheme implementations. Previously the old parser relied on #Guile -specific regular expressions.

This patch also implements a new feature where a stack trace is printed when an error occurs. This of course makes debugging much, much easier. Previously the old parser did not keep track of where code evaluation was happening, it simply produced lists without source location information. The new parser constructs an abstract syntax tree (AST) and source locations are attached to the branches of the tree which can be used in error reporting and stack traces.

Next I will make whatever minor tweaks might be necessary to get my Emacs Lisp interpreter run on other Scheme implementations, in particular MIT Scheme, Gambit, Stklos, and Gauche. I would also like to try to get it running on Chicken and Chez, although these are going to be a bit more tricky.

Then I will continue with the task of implementing a new declarative GUI library.

#tech #software #FOSS #FunctionalProgramming #Lisp #Scheme #SchemeLang #EmacsLisp #Emacs #Schemacs #GuileScheme