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.
Allows the use of `in-generator' to produce multiple values in a
position other than immediately within `for' (where the arity
can be inferred).
Closes PR 11662
The new parameter (and supporting environment variables and
command-line flags) can bytecode lookup to a tree other than
where a source file resides, so that sources and generated
compiled files can be kept separate. It also supports storing
bytecode files in a version-specific location (either with
the source or elsewhere).
The `make-log-receiver' function now includes a logger-name
filter. This filter is implemented as a low enough level that
it affects `log-level?' tests to check whether a log message
needs to be constructed at all.
The -W and -L flags and PLTSTDERR and PLTSYSLOG environment variables
support filters of the form "<level> <level>@<name> ...", where
<level>@<name> specializes filtering of events for a logger whose
name matches <name> to show <level> and higher.
Add `file-position*', which can return #f instead of raising
an exception when a port's position is unknown. Change
`make-input-port' and `make-output-port' to accept more
kinds of values as the initial position.
These changes make it possible to synchronize a port's
position with a `port-commit-peeked' action. It's ugly,
which I think reflect something broken about position
tracking in the port protocol (which seems difficult to fix
without breaking compaibility).
Providing a port instead of a reading or writing procedure
redirects the read/write to the specified port. This shortcut
is kind of a hack, but the run-time system can easily streamline
the redirection when it's exposed this way.
Using the new redirection feature reduces overhead in
`with-output-to-bytes' and `pretty-print'.
Since SIGHUP normally means that the output has gone away,
don't try to write to it.
Closes PR 13058 (although it doesn't solve the more general
problem that is noted in the PR)
