<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><HEAD> <META http-equiv=Content-Type content="text/html; charset=iso-8859-1"> <META content="MSHTML 6.00.6000.16735" name=GENERATOR> <STYLE></STYLE> </HEAD> <BODY bgColor=#ffffff> <DIV><FONT face="Courier New" size=2>Hi</FONT></DIV> <DIV><FONT face="Courier New" size=2></FONT> </DIV> <DIV><FONT face="Courier New" size=2>(define stream/c<BR> (promise/c<BR>  (or/c<BR>   null?<BR>   (cons/c any/c stream/c))))</FONT></DIV> <DIV><FONT face="Courier New" size=2></FONT> </DIV> <DIV><FONT face="Courier New" size=2>error: reference to an identifier before its definition: stream/c</FONT></DIV> <DIV><FONT face="Courier New" size=2></FONT> </DIV> <DIV><FONT face="Courier New" size=2>(define stream/c<BR> (flat-rec-contract strm<BR>  (promise/c null?)<BR>  (promise/c (cons/c any/c strm))))</FONT></DIV> <DIV><FONT face="Courier New" size=2></FONT> </DIV> <DIV><FONT face="Courier New" size=2>error: flat-rec-contract: expected flat contracts as arguments, got #<proj-contract></FONT></DIV> <DIV><FONT face="Courier New" size=2>I guess beacuse (promise/c expr) does not yield a flat contract.</FONT></DIV> <DIV><FONT face="Courier New" size=2></FONT> </DIV> <DIV><FONT face="Courier New" size=2>Is what I want possible? If yes, how?</FONT></DIV> <DIV><FONT face="Courier New" size=2></FONT> </DIV> <DIV><FONT face="Courier New" size=2>Thanks, Jos</FONT></DIV> <DIV><FONT face="Courier New" size=2></FONT> </DIV></BODY></HTML>