Comment by solomonb
13 hours ago
I prefer agda as proof checker but its not a practical choice for building software. Lean feels like it could legitimately become a successor to Haskell as the go to functional programming language for software development.
I think what holds Agda back from being "practical" is that it just doesn't have good tactics. You can't easily automate proofs and even simplification techniques require some language-level tricks[1]. There's technically support for elaborator reflection (as in Idris) but it's painful and impossible to debug. Certainly nowhere near where Coq and Lean are.
[1]: like this one I've used for several proofs so far: https://danilafe.com/blog/agda_expr_pattern/
Its also really slow and doesn't have a huge library ecosystem. The latter is fixable but not so much for the former.
Also true. The slowness is relatively unpredictable, too: sometimes changing a 'rewrite' to a 'with' can increase memory usage tenfold.
While we're at it, another major concern for me is the inscrutability of Agda's error messages. I've had one error message single-handedly overflow my tmux scrollback buffer. There's no way I'm going to be able to interpret that.
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