[plt-scheme] FrTime and existing libs

From: greg at cs.brown.edu (greg at cs.brown.edu)
Date: Mon May 24 14:17:30 EDT 2004


I'd like to thank everyone who's taken the time to try out FrTime (I really 
appreciate it), and also to apologize for responding so slowly to the discussion
that broke out on the mailing list earlier in the week.  (I'm out of the
country, and network access is limited and cumbersome.) 

As Noel Welsh points out, MzScheme procedures are not aware of signals, so they
are unlikely to work as intended in FrTime programs.  Moreover, the basic FrTime
language currently provides only a subset of MzScheme, enough to run the demo
programs but not much else.  (This is a change from earlier versions of FrTime,
and I'm sorry if it has caused confusion, but it should ultimately yield a much
more robust language.) 

To get signal-aware versions of other primitives, they need to be "lifted", 
using a special "require" form.  For example, to get lifted versions of 
"integer?" and "signal=?", one can write: 

(require (lift/strict mzscheme integer? signal=?)) 

Like with the standard "require", an arbitrary number of imports may be 
specified.  Imports are also allowed from modules other than MzScheme.  For 

(require (lift/strict (lib "etc.ss") build-list)) 

The basic FrTime will soon include most common MzScheme primitives, and we're 
also working on signal-aware versions of libraries like "list.ss" and "etc.ss". 
Until then, thank you for your patience, and I hope you'll continue to
experiment with the language.  I'll be providing more responsive support once I
return home. 


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