Thanks for the pointer!

I was able to compile and run the sample program Resize.hs (“ghc –make Resize.hs”), but when I load that module into GHCi and run main, I get a run-time error:

*Main> main
2016-01-02 16:24:42.245 ghc[52790:1003] *** Assertion failure in +[NSUndoManager _endTopLevelGroupings], /SourceCache/Foundation/Foundation-1056.17/Misc.subproj/NSUndoManager.m:328
2016-01-02 16:24:42.245 ghc[52790:1003] +[NSUndoManager(NSInternal) _endTopLevelGroupings] is only safe to invoke on the main thread.
2016-01-02 16:24:42.246 ghc[52790:1003] (
    0   CoreFoundation                      0x00007fff913b225c __exceptionPreprocess + 172
    1   libobjc.A.dylib                     0x00007fff93581e75 objc_exception_throw + 43
    2   CoreFoundation                      0x00007fff913b2038 +[NSException raise:format:arguments:] + 104
    3   Foundation                          0x00007fff90bb9361 -[NSAssertionHandler handleFailureInMethod:object:file:lineNumber:description:] + 189
    4   Foundation                          0x00007fff90b238ac +[NSUndoManager(NSPrivate) _endTopLevelGroupings] + 156
    5   AppKit                              0x00007fff914a7a23 -[NSApplication run] + 688
    6   libwx_osx_cocoau_core-3.0.0.2.0.dylib 0x0000000113101ce3 _ZN5wxApp10CallOnInitEv + 143
    7   libwx_baseu-3.0.0.2.0.dylib         0x00000001135eb396 _Z7wxEntryRiPPw + 47
    8   libwxc.dylib                        0x0000000115dfbd3c ELJApp_InitializeC + 124
    9   libHSwxcore-0.92.2.0-14assQ7lWYy0vwBRqyjk7D-ghc7.10.3.dylib 0x0000000114e8a5cc cc2eh_info + 132
)
2016-01-02 16:24:42.321 ghc[52790:1003] *** Assertion failure in +[NSUndoManager _endTopLevelGroupings], /SourceCache/Foundation/Foundation-1056.17/Misc.subproj/NSUndoManager.m:328
*Main>

A little googling found an issue: Crash when running a sample program in ghci on OSX. One comment recommends the following in ghci:

:set -fno-ghci-sandbox

When I use this command in a fresh ghci process (not after a crash), the sample works. However, when I run “main” a second time, the window doesn’t appear. Instead, I get some sort of undead process (called “ghc”) that I have to kill manually.

I installed wxWidgets via “brew update && brew install wxWidgets” and wxHaskell via “cabal update && cabal install wx”. I’m running Mac OS 10.9.5.

Has anyone gotten this latest wxHaskell to play well with ghci on Mac OS?

-- Conal