The use cases involve user-expandable grammars.
For example, consider the IRC nickname specification.
> They SHOULD NOT contain any dot character ('.', 0x2E).
> Servers MAY have additional implementation-specific nickname restrictions.
To implement this, we can do something along these lines:
```janet
(def nickname @{:main '(some :allowed)
:allowed (! (+ :forbidden/dot :forbidden/user))
# for lax mode, (put nickname :forbidden/dot false)
:forbidden/dot "."
# to add your own requirements
# (put nickname :forbidden/user 'something)
:forbidden/user false})
```
Additionally, it's common in parsing theory to allow matches of the
empty string (epsilon). `true` essentially allows for this.
Note that this does not strictly add new functionality, you could
emulate this previously using `0` and `(! 0)` respectively, but this
should be faster and more intuitive.
The speed improvement primarily comes from `(! 0)` which is now a single
step.
Previously, `*macro-lints*` was set after the `macroexpand1` fiber was
resumed, rather than just before. And, `*macro-lints*` was never
cleared. This behavior was typically fine since the main users of
`compile` pass the same lint array repeatedly, and the first macro
expansion (somewhere in boot.janet) never produces a lint. But, when
compiling with a fresh lint array, if the first macro invocation
produced a lint, the lint was always lost.
When suspended in `ev/give` or `ev/take`, closing the channel should
cause the result of `ev/give` or `ev/take` to be `nil`.
When suspended in `ev/select`, closing the channel should cause the
result of `ev/select` to be `[:close ch]`.
The results were flipped before.
When there is a bad arity function passed in to the fiber
constructor, return NULL so the runtime can choose what to do.
This is not the prettiest API but does work, and gives better error
messages for instance in the compiler.
Coming from commit 77189b6e66, relating
to changes in source mapping debug info, this caused a segfault when
traversing a stack frame where the birth_pc was incredibly large due
to wrap around. This fix prevents the wrap around and does saturating
subtraction to 0.
This removes unnecessary movn, movf, lds, and a few other instructions.
Any instructions that has not side effects and writes to a slot that
isn't used can be removed. A number of other optimizations can follow
from this:
- Implement the def-aliasing-var optimization better
- This function can be iterated as a fix point until no more
instructions are removed.
- If we implement slot renaming, then we no longer need to free slots
and can simplify the initial code generation a lot.
error: bad slot #1, expected string|symbol|keyword|buffer, got ...
error: bad slot #1, expected a string, symbol, keyword or buffer, got ...
bad s64 initializer: "donkey"
can not convert string "donkey" to s64
By take and releasing locks twice per channel in the case where nothing
is reading, there was an opportunity for ev/select to hang in the
multithreaded case. Also silence valgrind/helgrind errors.
Like getcstring, but operates on a byteview.
When writing bindings (i.e what capi.c is primarily used for), it's
common to want to accept a buffer *or* a string rather than just
a string.
For this, a byteview is perfect (and why not accept keywords while
you're at it?).
However, there's no built-in function for getting a cstring out of
a byteview, this adds one.
This also reformulates getcstring to be an edge-case of getcbytes
(simply adding an explicit check for stringness).
This turns splices that are ignored into compiler errors. Other
alternatives here should also be considered, for example making this
a compiler warning rather than an error. For example, the latest
spork as of a3ee63c137ee3234987dbbca71b566994ff8ae8c has an error of this
kind, but the resulting program does work correctly.
Also disallow splice propagation - code of the
form (+ 1 (do ;[2 3 4]) 5).
These now have semantic menaings that are pretty difficult to
work around. Code that tries to maniuplate user8 and user9 signals
right now may be affected
When peg/replace or peg/replace-all are given a function to serve as the text
replacement, any captures produced by the PEG are passed as additional
arguments to that function.
Functions will be invoked with the matched text, and their result will be
coerced to a string and used as the new replacement text.
This also allows passing non-function, non-byteviewable values, which will be
converted into strings during replacement (only once, and only if at least
one match is found).
there was a request to improve the error message, but the whole function
has non-informative errors. (both functions, actually, since the code is
duplicated)
as such, instead of catching it directly, address the assumption that
led to the SIGSEGV and let it be caught by the functions themselves,
thus reusing existing error messages (which can then be improved
separately).
When there is no format to be found after a %, get_fmt_mapping returns
NULL. It then gets called against strlen, which is a typical SEGV.
Check for NULL aginst mapping, which signals a null format being
specified.
While the old behavior was reasonable, it is not spelled out anywhere
in the documentation and was incidental rather than intentional.
Parameters of the same name of the function should probably take
precedence on name collision, following the principle of least surprise.
Comparison between different bracket and normal tuples
will now take into account the delimiter type. This solves strange
non-locality issues in the compiler due to this false equality, and is
more consistent with Janet's otherwise strong equality philosophy.
buffer/blit is difficult to use, and while buffer/push is the easiet
buffer manipulation function to use it only appends to the buffer.
buffer/push-at lets users manipulate buffers at any index - useful
for buffers used as an in-memory databases, for example.
