Commits on Jun 11, 2023

1. peg: add support for "true" and "false" primitives to always/never match …

   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.

   

   CosmicToast committed Jun 11, 2023
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2. fixup! peg: add support for "true" and "false" primitives to always/n… …

   …ever match

   

   CosmicToast committed Jun 11, 2023
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