hseq

hseq is a Haskell embedded domain-specific language for composing rhythmic sequences.

Install

Clone the project and run stack install Djembe. Next run stack setup then stack build.

OSX Setup

Open Audio MIDI Setup (Applications -> Utilities) and press ⌘2 (or go Window -> Show MIDI Window). Double click it IAC Driver, then check the box labeled "Device is online." Audio from Djembe should play through Garageband.

Example

Let's define a few quarter note length drum hits

bass  = n4 $ hsong (Hit BassDrum1 0 100)
snare = n4 $ hsong (Hit SnareDrum2 0 100)
hihat = n4 $ hsong (Hit ClosedHihat 0 100)

Now let's create a simple composition

beat = bass <> snare <> bass <> hihat

Finally we can play it at a specific tempo. In ghci (stack ghci):

> play beat 200

We can also compose beats using dseq notation

funky = dseq OpenHihat   8 ".... ...7 .... .7.."
     <> dseq ClosedHihat 8 "7777 777. 7777 7.77"
     <> dseq SnareDrum1  8 ".... 7..7 .7.7 7..7"
     <> dseq BassDrum1   8 "7.7. ..7. ..7. .7.."

Inspiration

• Bang
• The Haskell School of Music / Paul Hudak
• dseq