Backport fastgap fix

[yaxu]

fastgap got bugfixed in 2.0

Tidal/src/Sound/Tidal/Signal/Base.hs

Lines 462 to 482 in 2263c2e

	_fastGap :: Time -> Signal a -> Signal a
	_fastGap factor pat = splitQueries $ withEvent ef $ withQueryArcMaybe qf pat
	-- A bit fiddly, to drop zero-width queries at the start of the next cycle
	where qf (Arc b e) | bpos < 1 = Just $ Arc (cyc + bpos) (cyc + epos)
	| otherwise = Nothing
	where cyc = sam b
	bpos = min 1 $ (b - cyc) * factor
	epos = min 1 $ (e - cyc) * factor
	-- Also fiddly, to maintain the right 'whole' relative to the part
	ef ev = ev {whole = w', active = a'}
	where a = active ev
	b = aBegin a
	e = aEnd a
	a' = Arc (cyc + bpos) (cyc + epos)
	where cyc = sam b
	bpos = min 1 $ (b - cyc) / factor
	epos = min 1 $ (e - cyc) / factor
	w' = do w <- whole ev
	let b' = aBegin a' - ((b - (aBegin w)) / factor)
	e' = aEnd a' + (((aEnd w) - e) / factor)
	return $ Arc b' e'

Originally posted by @yaxu in #1076

As noticed by Claude: https://discord.com/channels/779427371270275082/779743442288377876/1347507824145731616

[claudeha]

this is the version I patched my local copy with, not sure if it is correct....

_fastGap :: Time -> Pattern a -> Pattern a
_fastGap 0 _ = empty
_fastGap r p = splitQueries $ p {query = map mungeResult . f}
  where
    r' = max r 1
    -- zero width queries of the next sam should return zero in this case..
    f st@(State a _)
      | start a' == nextSam (start a) = []
      | otherwise = query p st {arc = a'}
      where
        mungeQuery t = sam t + min 1 (r' * cyclePos t)
        a' = (\(Arc s e) -> Arc (mungeQuery s) (mungeQuery e)) a
    mungeResult e = e
      { whole = fmap (mungeArc (part e)) (whole e)
      , part = mungeArc (part e) (part e)
      }
    mungeArc (Arc s0 e0) (Arc s e) = Arc
      (sam s0 + ((s - sam s0) / r'))
      (sam s0 + ((e - sam s0) / r'))