Can't run DrRacket or gracket 7.0 - racket

Question

When I open DrRacket.app v7.0 on OSX 10.7.5, I get this error message:
LSOpenURLsWithRole() failed with error -10810 for the file /Applications/Racket v7.0/DrRacket.app.
Running drracket from the command line yields some more detail:
ffi-lib: couldn't open "/System/Library/Frameworks/CoreGraphics.framework/CoreGraphics.dylib" (dlopen(/System/Library/Frameworks/CoreGraphics.framework/CoreGraphics.dylib, 6): image not found)
context...:
"/Applications/Racket v7.0/share/pkgs/gui-lib/mred/private/wx/cocoa/utils.rkt": [running body]
for-loop
run-module-instance!125
for-loop
[repeats 1 more time]
run-module-instance!125
for-loop
[repeats 1 more time]
run-module-instance!125
for-loop
[repeats 1 more time]
run-module-instance!125
do-dynamic-require5
"/Applications/Racket v7.0/share/pkgs/gui-lib/mred/private/wx/platform.rkt": [running body]
for-loop
run-module-instance!125
...
Any suggestions for what I should try?
I figure that the problem is most likely that I'm running an old version of OSX. CoreGraphics was introduced in 10.8. I've looked for documentation on what OS versions each version of Racket requires, and haven't yet found anything. Does anyone know where it is?

Answer 1

Matthew Flatt kindly answered my question on the Racket github. DrRacket and gracket in Racket 7.0 will indeed run on OSXes earlier than 10.8. To get them to work:
Change line 41 of share/pkgs/gui-lib/mred/private/wx/cocoa/utils.rkt to:
(define cg-lib (ffi-lib (format "/System/Library/Frameworks/CoreGraphics.framework/CoreGraphics") #:fail (lambda () #f)))
In share/pkgs/gui-lib/mred/private/wx/cocoa/queue.rkt, change this line:
(define-cg CGEventTapCreate (_fun _uint32 _uint32 _uint32 _uint64
(_fun #:atomic? #t
#:keep mb-detect-box
_pointer _uint32 _id _pointer -> _id)
_pointer
-> _pointer))
to:
(define-cg CGEventTapCreate (_fun _uint32 _uint32 _uint32 _uint64
(_fun #:atomic? #t
#:keep mb-detect-box
_pointer _uint32 _id _pointer -> _id)
_pointer
-> _pointer) #:fail (lambda () #f))
and this line:
(define-cg CGEventGetLocation (_fun _pointer -> _NSPoint))
to:
(define-cg CGEventGetLocation (_fun _pointer -> _NSPoint) #:fail (lambda () #f))
These changes remove the dependency on CoreGraphics.