[plt-scheme] Scan key code in non-gui mode

Hi all

I'm a beginner in Scheme.  Is it possible to write a routine that can
detect a pressed key immediately and print out (byte or char) without
having to press "enter"?  So when a "spacebar" is pressed, the routine
will print out "32" right away.  I'm planning to write a non-gui app
so detecting the keyboard event throught scheme/gui seems like an
overkill to me.

Thanks in advance.