What does Pattern Double -> ControlPattern mean?

Okay so this might a super naive question but I'm not really into the programming languages world, but looking up the manual for all the functions in tidal I couldn't find a way of understanding how to interpret these terms, which lay beside every function. like if I read lpf :: Pattern Double -> ControlPattern, how should I actually use it? Hope I've been somewhat clear, thanks in advance to whoever will read me!

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Hi! Those are the type signatures for each function, describing the data types for the function’s inputs and outputs. This documentation page should help explain things further.

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I would like to extend the answer from the documentation (so looking to the documentation from @mindofmatthew first, would be useful).

The documentation tells you (correctly), that the last signature element is the return value. So for examlpe

:t fast 2
-- fast 2 :: Pattern a -> Pattern a

means that fast 2 expects one more pattern to return a pattern.

When we look into d1 then we will see, why something like d1 $ fast 2 will produces an error:

:t d1
-- d1 :: Pattern ValueMap -> IO ()

d1 expects the specific Pattern ValueMap and this is equal to ControlPattern and returns an IO() (creates the OSC messages as a stream inside Tidal) type.

type ControlPattern = Pattern ValueMap

That means you need the result type ControlPattern to use i.e. d1. When you look to functions like s, n, lpf etc. then you see why d1 $ s "bd" or d1 $ lpf 3000 works:

:t s 
--s "Pattern String -> ControlPattern

:t s "bd"
-- s "bd" :: ControlPattern

And because ControlPattern = Pattern ValueMap you can use it with d1

:t d1 $ s "bd"
-- d1 $ s "bd" :: IO()

I think this is everything you need to know for understanding the usage of ControlPattern. Everything beside this goes deeper to the innards I guess :slight_smile:

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