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Lark v0.8.0 Release Notes

Release Date: 2020-01-22 // over 4 years ago

  • - Better LALR

    🚀 The biggest change to this release is a new LALR engine, that is capable of dealing with a few edge cases that the previous parser couldn't.

    📜 This parser is supposed to be fully backwards-compatible with the previous one, but that is hard to verify!

    Thank you, @Raekye, for this great contribution to Lark!

    👀 For more details, see issue #418

    - Transformers now visit tokens, as well as rules (an alternative to lexer_callbacks)

    Transformer now visit tokens, in addition to rules.

    Simply define a method with the correct name (uppercase, of course), and the transformer will visit your tokens before the rules that contain them.

    🐎 It's possible to disable this, for backwards compatibility, or for the slight performance gain.

    - Other Changes

    ➕ Added visit_topdown methods to Visitor classes

    Lark now allows line comments in its rule definitions

    👍 Better error messages

    👌 Improvements to documentation

    🛠 Bugfixes

    0️⃣ maybe_placeholders is now the default (backwards-incompatible)** (REVERTED in 0.8.1)