Performance of pattern checker on OptCoercions

[Thomas Miedema]

Hi George,

here is an even simpler design!

When `-ffull-guard-reasoning` is on, use the new pattern match checker.

When `-ffull-guard-reasoning` is off (the default), try to use the new
pattern match checker, but if the number of guards is more than 20,
1. fall back to the old (simple) pattern match checker, and
2. issue a `too-many-guards` warning

The warning can be turned off with `-Wno-too-many-guards`.

What do you think?

Thomas


On Sat, Dec 19, 2015 at 7:52 PM, Thomas Miedema <thomasmiedema at gmail.com>
wrote:

> On Mon, Dec 14, 2015 at 3:03 PM, Richard Eisenberg <eir at cis.upenn.edu>
> wrote:
>
>> 1. -fwarn-pattern-guards=none
>> 2. -fwarn-pattern-guards=try
>> 3. -fwarn-pattern-guards=try-quiet
>> 4. -fwarn-pattern-guards=do   -- there is no "try"
>>
>
> The implementation
> <https://phabricator.haskell.org/rGHC7e216050ce0366a1d2c2a971db457a5d49f60e8a> now
> uses:
> 1. -guard-reasoning=simple
> 2. -guard-reasoning=try
> 3. -guard-reasoning=try-quiet
> 4. -guard-reasoning=do
>
> Since `try-quiet` suppresses a warning, it seems more consistent with the
> rest of the warning machinery to have a separate warning flag for it (`-Wornate-guards`,
> using the new syntax from #11218), enabled by default. When the fine-grained
> `-Werror=...` facility is implemented (#11219), this would allow you to for
> example say `-Werror -Wno-error=ornate-guards`, meaning: turn all warnings
> into errors, except for `-Wornate-guards` (but don't silence those
> completely!).
>
> So then it would like this (with `-f` prefix preferable):
> 1. -fguard-reasoning=simple
> 2. -fguard-reasoning=try
> 3. -fguard-reasoning=do
>
> And orthogonal to that: -Wornate-guards / -Wno-ornate-guards (name to be
> decided), which only have an effect when `-fguard-reasoning=try` (the
> default).
>
> Thomas
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.haskell.org/pipermail/ghc-devs/attachments/20151219/b33102c1/attachment.html>