Grammar is case sensitive?

I’m currently experimenting with lark, and am attempting to run the following code:

from lark import Lark

grammar = '''
    Stmt: "foo"
'''

parser = Lark(grammar, start='Stmt')

This results in the following exception:

Traceback (most recent call last):
  File "C:\Python35\lib\site-packages\lark\parsers\lalr_parser.py", line 31, in get_action
    return states_idx[state][key]
KeyError: 'RULE'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "tester.py", line 81, in <module>
    parser = construct_parser(grammar, root)
  File "tester.py", line 77, in construct_parser
    return Lark(lark_grammar, start=root)
  File "C:\Python35\lib\site-packages\lark\lark.py", line 143, in __init__
    self.grammar = load_grammar(grammar, source)
  File "C:\Python35\lib\site-packages\lark\load_grammar.py", line 537, in load_grammar
    tree = self.simplify_tree.transform( self.parser.parse(grammar_text+'\n') )
  File "C:\Python35\lib\site-packages\lark\parser_frontends.py", line 31, in parse
    return self.parser.parse(tokens)
  File "C:\Python35\lib\site-packages\lark\parsers\lalr_parser.py", line 60, in parse
    action, arg = get_action(token.type)
  File "C:\Python35\lib\site-packages\lark\parsers\lalr_parser.py", line 35, in get_action
    raise UnexpectedToken(token, expected, seq, i)
lark.common.UnexpectedToken: Unexpected token Token(RULE, 'tmt') at line 2, column 6.
Expected: dict_keys(['_COLON'])
Context: <no context>

However, when I convert the phrase Stmt to stmt, the grammar starts working.

Is this behavior intentional? I didn’t see anything in the documentation about this (unless I missed it?) and as far as I’m aware, both grammars are valid EBNF grammars – the casing of the non-terminals and terminals should be irrelevant (at least, according to the EBNF specification on wikipedia).

[erezsh]

No. You can open an issue with that feature request.

[erezsh]

If you mean the terminal values, then yes, of course. You do it by adding “i” to the end of the string or regexp.

Examples:

HELLO: "hello"i   // Match HELLO, Hello, hello, etc.
REGEXP: /this is [also] case? insensitive/i

You can mix them too:

some_rule: "Case Sensitive"  "insensitive"i  "Sensitive again"

Does that answer you question?