I have a package that uses platform dependent system libraries, each of which are separated out into there own package. Is there a way I could install a different dependency based on what platform I am installing on?
The most naive solution would be to have the package depend on all of them:
#lang info
...
(define deps '("mypackage-windows" "mypackage-osx"))
But then mypackage-windows and mypackage-osx get installed even if they're not needed. Worse still, I then need to ensure that the OS X and Windows specific packages don't cause issues when installed on the wrong platform.
So, there any way I can tell raco to only install the packages that I need based on each platform?
Yes there is. You can use the #:platform symbol in the deps portion of your info.rkt file to do this.
You can find documentation on it here, and an example of it in the racket-gui package.
You can use 'osx 'unix and 'windows to determine what platform you are on.
So your example would look like:
#lang info
...
(define deps '((mypackage-windows #:platform windows)
(mypackage-osx #:platform osx))
In fact, if you wanted to have a different version of your package that work differently on 36 and 64 (and even ppc) variants of each you can do that too:
#lang info
...
(define deps '((mypackage-windows-64 #:platform "win32\\x86_64")
(mypackage-windows-32 #:platform "wind32\\i386")
(mypackage-osx-64 #:platform "x86_64-macosx")
(mypackage-osx-32 #:platform "i386-macosx")
(mypackage-osx-ppc #:platform "ppc-macosx")))