Alex Shinn scripsit: > > Arguably, the "first time" the promise is forced is at line 9 in the > > example, and the "second time" is at line 6. However, at that time > > line 6 gets executed, no value has been computed *yet*, so presumably > > this example follows the spirit of the law.
[snip] > The example in question has been in the report since R4RS, so we can't > change this without breaking compatibility, and can't do that without > good reason. Prose trumps examples, though, and the prose really is ambiguous. It's not clear whether the value of a forced promise is determined at the beginning of the force or at its end, which makes it unclear whether the first time is really at line 6 after all. That's quite independent of threading considerations. -- John Cowan [email protected] http://ccil.org/~cowan Big as a house, much bigger than a house, it looked to [Sam], a grey-clad moving hill. Fear and wonder, maybe, enlarged him in the hobbit's eyes, but the Mumak of Harad was indeed a beast of vast bulk, and the like of him does not walk now in Middle-earth; his kin that live still in latter days are but memories of his girth and his majesty. --"Of Herbs and Stewed Rabbit" _______________________________________________ Scheme-reports mailing list [email protected] http://lists.scheme-reports.org/cgi-bin/mailman/listinfo/scheme-reports
