Using markovPat for chords

Questions and Answers
1

hey friends! I've been experimenting with bgold 's awesome markovPat .. trying to figure out how to use it with chords.

It works great with single notes or sounds;

this works fine:

p "bass" $  n (fmap ([0,4,7,11]!!) $ markovPat 32 1 [[4,1,0,0], [1,0,0.5,0.25], [1,0,0.5,0.25], [1,0,0,0]]) # thru

as does this:

p "drums" $ loopFirst $ (9 ~>) $ s (fmap (["bd", "808hh", "808ohh", "808sd", "~"]!!)
               $ markovPat 16 2
               [[2,4,1,0.5,3,0.5], -- bd
                [3,8,1,1,0.1,0.1], -- hh
                [3,7,0,0,2,1], -- ohh
                [1,0,0,0,0.2,0.8], -- sd
                [1,0.5,0.1,0,0.8,0.8], --rest
                [2,3,1,1,0.5,0.8] -- cvb
               ]) # cut 89

but this does not:

d1 $ n (fmap (["c'maj","e'min","a'min"]!!) $ markovPat 8 1 [[3,5,2], [4,4,2], [0,1,0]]) # thru

(thru is midi output)

I get an error like this:

<interactive>:21270:16: error:
    • No instance for (Data.String.IsString Double)
        arising from the literal ‘"c'maj"’
    • In the expression: "c'maj"
      In the first argument of ‘(!!)’, namely
        ‘["c'maj", "e'min", "a'min"]’
      In the first argument of ‘fmap’, namely
        ‘(["c'maj", "e'min", "a'min"] !!)’

any ideas? thanks!

1 Like
2

Here, 0,4, .. are numbers:

n (fmap ([0,4,7,11]!!) $ ...

there, "c'maj" etc. are patterns:

n (fmap (["c'maj","e'min","a'min"]!!) $ ..

Your program has this value and type (using a smaller example)

(fmap (["c'maj","d" :: Pattern Note] !!) $ run 2)
(0>½)|(0>1)|Note {unNote = 0.0}
(0>1)|Note {unNote = 4.0}
(0>1)|Note {unNote = 7.0}
(½>1)|(0>1)|Note {unNote = 2.0}
it :: Pattern (Pattern Note)

so you need one of the join operators (and I always confuse them) but perhaps

n $ unwrap (fmap (["c'maj","d" :: Pattern Note] !!) $ run 2)
(0>½)|n: Note {unNote = 0.0}n
(0>½)|n: Note {unNote = 4.0}n
(0>½)|n: Note {unNote = 7.0}n
(½>1)|n: Note {unNote = 2.0}n
it :: ControlPattern

The examples from the documentation (https://tidalcycles.org/markovPat) use s where you want n, and the types are different

n :: Pattern Note -> ControlPattern
s :: Pattern String -> ControlPattern

Since s accepts any string, we risk running into this

s (fmap (["[bd,sn]", "cp", "arpy" ]!!) $ markovPat 8 1 [[3,5,2], [4,4,2], [0,1,0]])
(0>⅛)|s: "cp"
(⅛>¼)|s: "[bd,sn]"  <== wrong
...

I think the more expressive type of n is good (it turns a run-time error into a compile-time error).