\begin{code}
#include "rtsdefs.h"

void
OutOfHeapHook (request_size)
  W_ request_size; /* in bytes */
{
    W_ heap_size = RTSflags.GcFlags.heapSize * sizeof(W_); /* i.e., in bytes */

    fprintf(stderr, "Heap exhausted;\nwhile trying to allocate %lu bytes in a %lu-byte heap;\nuse `+RTS -H<size>' to increase the total heap size.\n",
	request_size,
	heap_size);
}
\end{code}