Simplify rev

[yaxu]

I think @polymorphicengine pointed out that rev could just negate time, rather than the complex mirroring it's doing now.

Here's an implementation of that:

negateArc (Arc b e) = Arc (negate e) (negate b)
rev' = withQueryArc negateArc . withResultArc negateArc

Can we drop this in or does it have different behaviour? I think it's similar but the cycles are also in reverse order?

for comparison:

Tidal/src/Sound/Tidal/Pattern.hs

Lines 813 to 845 in 493b2c0

	rev :: Pattern a -> Pattern a
	rev p =
	keepMeta p $
	splitQueries $
	p
	{ query = \st ->
	map makeWholeAbsolute $
	mapParts (mirrorArc (midCycle $ arc st)) $
	map
	makeWholeRelative
	( query
	p
	st
	{ arc = mirrorArc (midCycle $ arc st) (arc st)
	}
	)
	}
	where
	makeWholeRelative :: Event a -> Event a
	makeWholeRelative e@Event {whole = Nothing} = e
	makeWholeRelative (Event c (Just (Arc s e)) p'@(Arc s' e') v) =
	Event c (Just $ Arc (s' - s) (e - e')) p' v
	makeWholeAbsolute :: Event a -> Event a
	makeWholeAbsolute e@Event {whole = Nothing} = e
	makeWholeAbsolute (Event c (Just (Arc s e)) p'@(Arc s' e') v) =
	Event c (Just $ Arc (s' - e) (e' + s)) p' v
	midCycle :: Arc -> Time
	midCycle (Arc s _) = sam s + 0.5
	mapParts :: (Arc -> Arc) -> [Event a] -> [Event a]
	mapParts f es = (\(Event c w p' v) -> Event c w (f p') v) <$> es
	-- Returns the `mirror image' of a 'Arc' around the given point in time
	mirrorArc :: Time -> Arc -> Arc
	mirrorArc mid' (Arc s e) = Arc (mid' - (e - mid')) (mid' + (mid' - s))

[sss-create]

A quick test worked great! Wow, what a simplification.

[polymorphicengine]

i guess the difference comes in once a pattern is longer than one cycle:
currently rev <[1 2] [3 4]> == <[2 1] [4 3]>, but with the above (i think) it would be <[4 3] [2 1]>, so yes the cycles are also in reverse order

i think both behaviors are useful

[yaxu]

Yes we could call the new one something like revall or revpat