Note that this branch is built using nightly 'master' zig. The more actively developed branch is zig-0.9.x. Changes are periodically merged from there to this branch.
At least, the beginnings of one.
This is partly to learn Zig,
partly to have a fast verifier that I can hack
(Python is way too slow, Rust is too weird for me still, Nim seems less clean, C is out),
so that I can perhaps one day try to do experiments around
parsing (where parse tree of X... is proof of |- TOPLEVEL X... ),
abbreviations,
and modules.
Build using Zig master, then just run the resulting binary, passing a single .mm file on the command line.
For example, use set.mm, which you can get from metamath.org, or download the most recent version directly from GitHub: https://github.com/metamath/set.mm/raw/develop/set.mm.
The version of the Metamath specification that was implemented, is the one from the 2nd edition Metamath book. (Norman D. Megill, David A. Wheeler, "Metamath: A Computer Language for Mathematical Proofs". Lulu Press, 2019. http://us.metamath.org/downloads/metamath.pdf .)
Verifier completeness:
-
Verify that 'normal' tokens don't start with
$, label tokens use only allowed characters, etc. -
Support
?in proofs.
Clean up:
-
Clean-up / refactor RuleIterator + ScopeDiff: Add methods, move functionality between these structs. Also encapsulate some parts. Also try to avoid duplication in statement handling.
-
Work towards a library that can also be used for $a/$p/$e parse trees.
Functionality:
- Generate a parse tree for every $a/$p/$e statement.
If possible/feasible, check that it is the only possible parse tree.
Try to also support 'conditional syntax rules,
so e.g.
${ $e -. B = 0 $. $a class ( A / B ) $. $}which expresses thatA / Bis only a syntactically valid expression ifBis not zero.
Verifier performance:
-
Optimize performance by reducing memory use: A token is currently represented by a Zig slice (= pointer and a length), and this could be replaced by a single small(ish) integer by 'interning' all tokens.
-
Optimize performance by parallelizing using Zig
async. -
Optimize performance by reducing memory use: I suspect ArrayList is not the right data structure for some of the lists.
Verifier tests:
-
Run the test suite from https://github.com/david-a-wheeler/metamath-test probably by checking it out as a Git submodule and using the zig-mm-verify binary as the approved-or-not judge.
-
(Separate project.) Extend that test suite, to capture as many as possible deviations from the specification as possible.
Verifier usability:
-
Identify the location (line/column) of at least the first error.
-
Don't use 'error union' for Metamath verification errors.
Language dialects:
- Optional modes where $c/$v is allowed to be duplicated
(useful to create set-parsed.mm which declares stuff before
$[ set.mm $]); where $f implicitly does $c/$v; and perhaps more.