Re: Tree Sitter (was Re: cc-mode fontification feels random)

[Stephen Leake]

Richard Stallman <rms@gnu.org> writes:

> [[[ To any NSA and FBI agents reading my email: please consider    ]]]
> [[[ whether defending the US Constitution against all enemies,     ]]]
> [[[ foreign or domestic, requires you to follow Snowden's example. ]]]
>
> The features that the DoD liked so much about Ada, to me make it feel
> very clunky.  You have to declare so much!

Yes, and then the compiler checks everything for you, so the code is
much more likely to be correct before you start testing.

It also helps when modifying/extending code; if it doesn't compile,
you've done something wrong, and the error messages point to what to
fix.

In addition, SPARK (https://www.adacore.com/sparkpro) is a formal proof
system designed for Ada, giving you even more power to build programs
that are correct.

A long time ago, I was working on a system that was programmed in C++. I
re-implemented it in Ada; it was pretty clear that I could write correct
code at least 4 times faster in Ada than in C++. Now I only write code
in something other than Ada if there is no way to use Ada (for example,
my music app on Android is in Java; it's nominally possible to write Ada
code for Android, but it takes a _lot_ of work, and would break with
every new release of Android).

> What advantages does wisi.el's Ada module have over Tree Sitter?

That's not entirely clear yet. I believe the error recovery in wisi is
more powerful than tree-sitter's, but I'm probably biased, and it's
hard to come up with a good objective metric until we get both fully
integrated into Emacs. It is clear that good error recovery is essential
to implementing indentation using a parser; tree-sitter is not
advertised as supporting indentation, while indentation is a primary
purpose of wisi.

The parser generator in wisi is more powerful in some ways; it can
handle LR1 table generation for Ada, using a grammar that closely
follows the grammar in the Ada Language Reference Manual; tree-sitter
can't handle that. tree-sitter could probably handle it if someone
spends time simplifying/optimizing the grammar.

The tree-sitter parser generator allows specifying token precedence to
resolve grammar conflicts; wisi has no support for that (it could be
added).

tree-sitter has been around for a while, and there are many people and
editors using it and working on it. wisi is just me working on it, and
Emacs using it for ada-mode.

tree-sitter also provides bindings to the parser for other languages.
That is possible with wisi, but I don't have the bandwidth for it.

-- 
-- Stephe