<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><HEAD> <META content="text/html; charset=us-ascii" http-equiv=Content-Type> <META name=GENERATOR content="MSHTML 11.00.9600.16521"></HEAD> <BODY> <DIV><FONT size=2 face="Courier New"><SPAN class=595591418-01042014>Something went wrong with my previous email. Sorry. I try again.</SPAN></FONT></DIV> <DIV><FONT size=2 face="Courier New"><SPAN class=595591418-01042014></SPAN></FONT> </DIV> <DIV><FONT size=2 face="Courier New"><SPAN class=595591418-01042014>Hi.</SPAN></FONT></DIV> <DIV><FONT size=2 face="Courier New"><SPAN class=595591418-01042014>First of all congratulations with version 6.0. Very mice indeed.</SPAN></FONT></DIV> <DIV><SPAN class=595591418-01042014> <DIV><FONT size=2 face="Courier New"><SPAN class=523433217-01042014>The streams as provided by racket/stream are very nice and much simpler than in srfi 41.</SPAN></FONT></DIV> <DIV><FONT size=2 face="Courier New"><SPAN class=523433217-01042014><SPAN class=595591418-01042014>two remarks though.</SPAN></SPAN></FONT></DIV> <DIV><FONT size=2 face="Courier New"><SPAN class=523433217-01042014><SPAN class=595591418-01042014></SPAN></SPAN></FONT> </DIV> <DIV><FONT size=2 face="Courier New"><SPAN class=523433217-01042014><SPAN class=595591418-01042014>one.</SPAN></SPAN></FONT></DIV> <DIV><FONT size=2 face="Courier New"><SPAN class=523433217-01042014><SPAN class=595591418-01042014>racket/stream duplicates code as found in racket/promise too.</SPAN></SPAN></FONT></DIV> <DIV><FONT size=2 face="Courier New"><SPAN class=523433217-01042014><SPAN class=595591418-01042014>This is necesssary, of course, for otherwise we could not discern streams from promises.</SPAN></SPAN></FONT></DIV> <DIV><FONT size=2 face="Courier New"><SPAN class=523433217-01042014><SPAN class=595591418-01042014>It would be nice if racket/promise would provide a tool for the definition of subtypes of promises.</SPAN></SPAN></FONT></DIV> <DIV><FONT size=2 face="Courier New"><SPAN class=523433217-01042014><SPAN class=595591418-01042014>Such a tool would have to define (at least) a predicate (procedure) and two constructors (syntaxes), one for lazy and one for delay.</SPAN></SPAN></FONT></DIV> <DIV><FONT size=2 face="Courier New"><SPAN class=523433217-01042014><SPAN class=595591418-01042014></SPAN></SPAN></FONT> </DIV> <DIV><FONT size=2 face="Courier New"><SPAN class=523433217-01042014><SPAN class=595591418-01042014>two</SPAN></SPAN></FONT></DIV> <DIV><FONT size=2 face="Courier New"><SPAN class=523433217-01042014><SPAN class=595591418-01042014>I miss something that I call stream-lazy.</SPAN></SPAN></FONT></DIV> <DIV><FONT size=2 face="Courier New"><SPAN class=523433217-01042014><SPAN class=595591418-01042014>When using racket/stream, I define:</SPAN></SPAN></FONT></DIV> <DIV><FONT size=2 face="Courier New"><SPAN class=523433217-01042014><SPAN class=595591418-01042014>(define-syntax-rule (stream-lazy def/expr ...)</SPAN></SPAN></FONT></DIV> <DIV><FONT size=2 face="Courier New"><SPAN class=523433217-01042014><SPAN class=595591418-01042014> (stream-cdr (stream-cons 'who-cares? (let () def/expr ...))))</SPAN></SPAN></FONT></DIV> <DIV><FONT size=2 face="Courier New"><SPAN class=523433217-01042014><SPAN class=595591418-01042014>When using srfi 41, I define:</SPAN></SPAN></FONT></DIV> <DIV><FONT size=2 face="Courier New"><SPAN class=523433217-01042014><SPAN class=595591418-01042014>(define-syntax-rule (stream-lazy def/expr ...)</SPAN></SPAN></FONT></DIV> <DIV><FONT size=2 face="Courier New"><SPAN class=523433217-01042014><SPAN class=595591418-01042014> ((stream-lambda () def/expr ...)))</SPAN></SPAN></FONT></DIV> <DIV><FONT size=2 face="Courier New"><SPAN class=523433217-01042014><SPAN class=595591418-01042014></SPAN></SPAN></FONT> </DIV> <DIV><FONT size=2 face="Courier New"><SPAN class=523433217-01042014><SPAN class=595591418-01042014>Just my two cents.</SPAN></SPAN></FONT></DIV> <DIV><FONT size=2 face="Courier New"><SPAN class=523433217-01042014><SPAN class=595591418-01042014>Jos</SPAN></SPAN></FONT></DIV> <DIV><FONT size=2 face="Courier New"><SPAN class=523433217-01042014><SPAN class=595591418-01042014></SPAN></SPAN></FONT> </DIV></SPAN></DIV></BODY></HTML>