2.4 KiB
SuperCollider Racket library
Goal
I planned on writing a client for the SuperCollider (SC) music synthesis server for use in the Music Programming section of CSC123. Using the interface to SuperCollider, students will have access to real-time synthesis techniques.
First hope
In the first quarter, after examining implementations in various languages, I set out on creating a new implementation in Racket from scratch. Quickly, however, it appeared that two quarters is not enough time, so I looked into porting the scheme implementation of a supercollider client, rsc3, to Racket.
The Porting process
I first tried rsc3 in a scheme interpreter, including ikarus and DrRacket's r6rs mode (#lang r6rs). rsc3 ran with very little modification (one library funciton name was wrong). However, rsc3 could not be installed as a Racket package, due to a conflict of the way scheme and racket handle libraries. Installing rsc3 as a package is an important aspect since that is how students will install rsc3.
What I did is instead of using "#lang r6rs", which makes racket behave like a scheme interpreter confirming to the r6rs scheme standard, I used "#lang racket" and imported the rnrs library that has scheme functions in a racket environment. This way I could use Racket's provide and package functionality works.
The process of porting was relatively straightforward. I compiled a file, looked for errors, and fixed them. Some defined utility functions were not necessary because racket had native implementations.
Challenges when porting
One tricky part was a difference in the list representations between r6rs scheme and Racket. Racket uses mutable pairs to construct lists, while scheme uses immutable pairs. This makes it so that a list created in Racket cannot be used in a scheme function that accepts a list. One way around this is to construct lists using mcons in Racket then pass it to a scheme function.
Features added
It would be hard for first year students to use rsc3 directly, so I created simplified functions to perform common tasks of creating and controlling sounds.
Instruments
One main feature of SuperCollider is the Synthdef.
Students could create instruments with parameters that could be changed in real-time.
Outline
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scratch & porting rsc3
- how I started
- challenges
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features
- instruments
- sliders
- effect chaining
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cross platform