Issues

• TextSlice accepts an end past the text

  lark-parser/lark#1659 · Filter by author SashaMIT opened on Oct 1, 2026

• Zero-width regex terminal rejected even when the surrounding rule can never match zero characters

  lark-parser/lark#1640 · Filter by author monperrus opened on Aug 16, 2026
  1

• Invalid Tree structure and anti-patterns in lark/tests/test_pattern_matching.py

  lark-parser/lark#1608 · Filter by author M-Rehan-S opened on Jun 13, 2026

• TextSlice implementation breaks codebases based on 1.2.2

  lark-parser/lark#1599 · Filter by author ysard opened on Jun 1, 2026
  5

• Optional closing tag causes runtime error: Earley generates multiple start symbol items

  lark-parser/lark#1587 · Filter by author caph1993 opened on Apr 9, 2026
  1

• Infinite loop in lalr and cyk

  bug
  lark-parser/lark#1585 · Filter by author acornlaw-skwilinski opened on Mar 24, 2026
  3

• Export and document lark.tools.standalone.gen_standalone

  enhancement
  lark-parser/lark#1583 · Filter by author fyellin opened on Mar 23, 2026
  2

• __default_token__ and __default__ not called for Lark(transformer=transformer).

  lark-parser/lark#1582 · Filter by author fyellin opened on Mar 23, 2026
  7

• contextual lexer accept set seems wrong

  question
  lark-parser/lark#1581 · Filter by author MartyMcFlyInTheSky opened on Mar 23, 2026

• The version on https://pypi.org/project/lark-parser/ is 0.12.0

  question
  lark-parser/lark#1574 · Filter by author KeithSloan opened on Feb 13, 2026
  2

• python.lark failed to pare special forms of with_stmt

  lark-parser/lark#1570 · Filter by author Joxos opened on Dec 7, 2025
  2

• Allow rules in templates

  enhancement
  lark-parser/lark#1566 · Filter by author Sporarum opened on Oct 31, 2025
  2

• Improve memory usage in the contextual lexer ?

  discussionenhancement
  lark-parser/lark#1539 · Filter by author erezsh opened on Jul 5, 2025

• Misaligned error location when input text contain full-width characters

  lark-parser/lark#1530 · Filter by author johan456789 opened on Apr 24, 2025
  2

• Add support for the a and L regex flags

  enhancementgood first issue
  Feature

  lark-parser/lark#1527 · Filter by author erezsh opened on Apr 21, 2025
  5

• Parsing bytestrings and token values

  bug
  lark-parser/lark#1526 · Filter by author createyourpersonalaccount opened on Apr 18, 2025
  3

• Lark needs a favicon

  enhancementIDE
  lark-parser/lark#1510 · Filter by author nchammas opened on Jan 24, 2025
  4

• Matching line continuation in shell style comment

  question
  lark-parser/lark#1509 · Filter by author kevemueller opened on Jan 23, 2025
  3

• Move documentation to bootstrap 5

  docsgood first issuehelp wanted
  lark-parser/lark#1494 · Filter by author wiene opened on Nov 30, 2024
  2

• Difference in LALR Grammar Parsing

  question
  lark-parser/lark#1489 · Filter by author Crayon112 opened on Nov 16, 2024

• Ignored terminal used in the grammar is expected with Earley but not with LALR

  add to docsbug
  lark-parser/lark#1473 · Filter by author Molrn opened on Sep 26, 2024
  3

• Syntactic sugar: Tree.has_data()

  enhancement
  lark-parser/lark#1465 · Filter by author makukha opened on Sep 11, 2024
  5

• Lark resulting LALR -nor- Earley parser will pick out the longest match of say "a + b + c + ... + d" example input. Bug (?)

  lark-parser/lark#1463 · Filter by author FruitfulApproach opened on Sep 4, 2024
  1

• Generate counter-examples for conflicts in LALR parsing

  enhancement
  lark-parser/lark#1449 · Filter by author BenzoX opened on Aug 16, 2024
  3

• Terminal collision when importing the same terminal from different grammars

  discussionenhancement
  lark-parser/lark#1448 · Filter by author erezsh opened on Aug 15, 2024