Aziz wrote: > > Why, pray tell, must the third argument to fxcopy-bit-field > > be less than (fixnum-width)? > > So that your code would still work when you do > (declare unsafe non-r6rs full-speed-forward) > and without the compiler coercing the value of > the shift to some small value. This also forces > implementors to implement these operations in a > portable, predictable, reliable, and safe manner.
Since your declaration is already outside the bounds of R6RS, implementations are permitted to respond to it by transforming the semantics in arbitrary ways. Hence the R6RS spec in no way forces implementors to implement operations in a portable, predictable, reliable, or safe manner in programs governed by your declaration. What you are trying to say, I think, is that excluding the sign bit from bit fields assists portability and predictability in R6RS programs that contain no such declarations, but all bets are off when you do (declare unsafe non-r6rs full-speed-forward). Will _______________________________________________ r6rs-discuss mailing list [email protected] http://lists.r6rs.org/cgi-bin/mailman/listinfo/r6rs-discuss
