-@installHandler int handler iset@ calls @sigaction@ to install
-an interrupt handler for signal @int@. If @handler@ is
-@Default@, @SIG_DFL@ is installed; if @handler@ is
-@Ignore@, @SIG_IGN@ is installed; if @handler@ is
-@Catch action@, a handler is installed which will invoke @action@ as a
-replacement for @main@. If @iset@ is @Just s@, then the
-@sa_mask@ of the @sigaction@ structure is set to @s@;
-otherwise it is cleared. The previously installed signal handler for
-@int@ is returned.
+@installHandler int handler iset@ calls @sigaction@ to install an
+interrupt handler for signal @int@. If @handler@ is @Default@,
+@SIG_DFL@ is installed; if @handler@ is @Ignore@, @SIG_IGN@ is
+installed; if @handler@ is @Catch action@, a handler is installed
+which will invoke @action@ in a new thread when (or shortly after) the
+signal is received. See Section <ref name="Concurrent Haskell"
+id="concurrent-haskell"> for details on how to communicate between
+threads.
+
+If @iset@ is @Just s@, then the @sa_mask@ of the @sigaction@ structure
+is set to @s@; otherwise it is cleared. The previously installed
+signal handler for @int@ is returned.