withSystemRandom test case

output

$ ghc --make foo
[1 of 1] Compiling Main             ( foo.hs, foo.o )
Linking foo ...
$ ./foo
"Starting IO"
Warning: Couldn't open "/dev/urandom"
Warning: using system clock for seed instead (quality will be lower)
"Starting IO"
foo: nonexitant: openFile: does not exist (No such file or directory)

test.hs

import System.Random.MWC

main = withSystemRandom $ const $ do
  print "Starting IO"
  putStrLn =<< readFile "/nonexitant"