There is the rtsSupportsBoundThreads
value value in Control.Concurrent
for this. For example:
module Main (main) where
import Control.Concurrent
main :: IO ()
main = print rtsSupportsBoundThreads
And during test:
$ ghc -fforce-recomp Test.hs; ./Test
[1 of 1] Compiling Main ( Test.hs, Test.o )
Linking Test ...
False
$ ghc -fforce-recomp -threaded Test.hs; ./Test
[1 of 1] Compiling Main ( Test.hs, Test.o )
Linking Test ...
True
Here is its C-part source code:
HsBool
rtsSupportsBoundThreads(void)
{
#if defined(THREADED_RTS)
return HS_BOOL_TRUE;
#else
return HS_BOOL_FALSE;
#endif
}