@kha This modification saved 150k object allocations on my machine.
BTW, the function
```
def command_parser.run (commands : list command_parser) (p : command_parser)
: parser_t command_parser_config id syntax :=
λ cfg, (p.run cfg).run_parsec $ λ _, any_of $ commands.map (λ p, p.run cfg)
```
is also affected by the problem I described at Zulip. It is another
example where eager eta-expansion is bad. Every time we call it, we
will create approx. 20 closures and 20 cons memory cells. We have at
least 600 commands in core.lean. So, just the `map` nested there will
generate 24k memory allocations. Moreover, the problem will get worse as we add
more commands.
1cb22b6801