The previous for/fold/derived examples in the docs
incorrectly expanded, placing the entire body of the
user defined for loop into a let expression inside of
for/fold/derived. This meant that break clauses (i.e. #:break
or #:final) that appeared in the body of the user-defined
for loop were not visible to the underlying for/fold/derived
macro after expansion and therefore usages of #:break or #:final
incorrectly resulted in syntax errors (since with the incorrect
expansion, they were seemingly misplaced keywords inside of a let).
With this PR the for/fold/derived examples in the docs now
expand correctly into a form that mirrors the actual
expected syntax of for loops:
(user-defined-for (for-clause ...) body-or-break ... body)
==(now expands more or less into)==>
(for/fold/derived (for-clause ...) body-or-break ... body)
Or in other words, the body of the user defined for loop now correctly
expands directly into the body of for/fold/derived.
Adjust list and stream handling as sequences so that during the body
(for ([i (in-list l)])
....)
then `i` and its cons cell in `l` are not implicitly retained while
the body is evaluated. A `for .... in-stream` similarly avoids
retaining the stream whose head is being used in the loop body.
The `map`, `for-each`, `andmap`, and `ormap` functions are similarly
updated.
The `make-do-sequence` protocol allows an optional extra result so
that new sequence types could have the same properties. It's not clear
that using `make-do-sequence` is any more useful than creating the new
sequence as a stream, but it was easier to expose the new
functionality than to hide it.
Making this work required a repair to the optimizer, which would
incorrectly move an `if` expression in a way that could affect
space complexity, as well as a few repairs to the run-time system
(especially in the vicinity of the built-in `map`, which we should
just get rid of eventually, anyway).
* Wrong contract for syntax-local-value in the documentation.
* Clarified signature in documentation for expand-import, expand-export and pre-expand-export
* Corrected typo in documentation for "for".
* Fixed error message for function which seems to have been renamed in the docs
* Fixed typo in a comment in the tests
* Fixed a typo in the documentation for set-subtract.
* Use double ellipses for the free-id-table-set*, free-id-table-set*!, bound-id-table-set* and bound-id-table-set*! operations
Port `examples`, `interactions`, etc., to use the new `examples`
form of `scribble/examples`. The main intended effect is to ensure
that errors are produced by examples only as specifically
indicated.
