Support for break clauses complicates expansion to `for/fold/derived';
a new `syntax/for-body' library provides a helper for macros that need
to split a `for'-style body into a prefix part and wrappable part.
Now use for/fold to thread the index through the iteration form, so
that all variants can take advantage of the optional #:length
argument. Previously, only the for/vector and for/flvector used the
The behavior when #:length does not match the number of iterations has
changed: iteration stops when either the vector is full, or the
requested number of iterations has been achieved, whichever comes
first. If #:length is larger than the number of iterations performed,
then the remaining slots in the vector are filled with the default
argument of (make-vector ...), which is currently 0.
- Now the faster forms take a #:length keyword to designate the length
of the vector to pre-allocate.
- The for/[fl]vector forms take multiple body expressions and set the
vector component to the value of the last one.
- When given a #:length argument, the for/vector and for/flvector
forms check that the iteration is not exceeding the given length,
raising exn:fail if it does.
- Test cases for the multiple body expressions and the exception for
excessive iterations have been added.
- Doc modifications to bring the docs in line with the new forms.
- Doc modifications to note that the #:length versions of the form
*may* all the computation to be performed more efficiently, and
stating that it "is an error" if the given length-expr does not
produce a valid length for a vector that matches the number of
iterations for the loop.
- Note that no test is made for a number of loop iterations that is
smaller than the given vector length. Also, the for*/[fl]vector
forms do not optimize when given a #:length argument. These are
areas for future improvement.
punctuations outside of the form, as it does with quote punctuations.
So things like this
#, @foo{...}
that required the space to make the @foo read as a scribble form are
now better written as
@#,foo{...}
This changes all such occurrences. (In case you see this change in
your files and are worried that there might be changes: I mechanically
verified that the result of `read'ing the modified files is identical
to the previous version.)
svn: r15111
