Support for GHC-8.8

[sjakobi]

The issues I'm aware of:

• Bump upper bound on hashable
• regex-posix is currently blocked on Build error with GHC 8.8.1 ChrisKuklewicz/regex-tdfa#23.

[sjakobi]

Apparently the library dependency on regex-posix is only needed for the assertBodyContains function:

snap-core/src/Snap/Internal/Test/Assertions.hs

Lines 160 to 168 in 0b45d71

	assertBodyContains :: ByteString -- ^ Regexp that will match the body content
	-> Response
	-> Assertion
	assertBodyContains match rsp = do
	body <- getResponseBody rsp
	assertBool message (body =~ match)
	where
	message = "Expected body to match regexp \"" ++ show match
	++ "\", but didn't"

How about moving that function behind a flag or using a better-maintained regex library?

Actually for the uses in this package, Data.ByteString.isInfixOf would probably be good enough…

[tom-audm]

Removing the regex-posix dependency would be awesome! If this looks okay to the maintainers I'd be happy to do the work here.

[tom-audm]

@sjakobi unfortunately Data.ByteString.isInfixOf isn't enough for all uses within snap-core.

WIP for removing the dependency is here: #289

I removed assertBodyContains :: ByteString -> Response -> Assertion so as not to create silent test breakage, and replaced it with:

• assertBodyMatches :: String -> (ByteString -> Bool) -> Response -> Assertion (the first String is a label for test failure messages)
• assertBodyContainsBS :: ByteString -> Response -> Assertion which uses assertBodyMatches with Data.ByteString.isInfixOf

The code which still requires regex-posix at the moment is:

• https://github.com/snapframework/snap-core/blob/master/test/Snap/Internal/Http/Types/Tests.hs#L56-L59
• https://github.com/snapframework/snap-core/blob/master/test/Snap/Test/Tests.hs#L297-L299

[sjakobi]

@tom-audm Removing regex-posix as a library dependency is a big step forward!

Regarding the test dependency we could either wait for a new release (haskell-infra/hackage-trustees#238 looks promising), or switch to a different regex package.

[tom-audm]

A third option is to rewrite those two remaining tests with attoparsec, which is already a dependency, thus fully removing the dependency!

[sjakobi]

@gregorycollins, @mightybyte, do you have an opinion on how to go forward here?

[sjakobi]

@gregorycollins @mightybyte

Now that regex-posix is compatible with GHC-8.8, can you please make a new release?

[domenkozar]

Needs conditionals around https://github.com/snapframework/snap-core/blob/master/src/Snap/Internal/Core.hs#L314, otherwise it compiles on 8.8

[sjakobi]

Ping @gregorycollins @mightybyte! :)

[dten]

#290 but the test fail on 7.8 or less but i can't figure out why
edit: got it.. silly me

[kindaro]

I suppose this should be closed since #290 is merged?