Question 1

sedlex vs ocamllex: which one should I use for my OCaml project?

Accepted Answer

Choose sedlex if you need Unicode support or prefer embedded lexer specs in OCaml syntax. Opt for ocamllex if you're handling only ASCII, want separate lexer files, or need slightly better performance for simple cases.

Question 2

How to capture named groups in sedlex regex patterns?

Accepted Answer

Use OCaml's 'as' pattern syntax within regexps, like (Plus digit as num). Extract the sub-match with functions like Sedlexing.Utf8.of_submatch to get the string value, but note restrictions inside repetition operators.

Question 3

Does sedlex work with UTF-16 encoded files?

Accepted Answer

Yes, sedlex supports UTF-16 encoding through the Sedlexing module, which provides functions to create lexbufs from UTF-16 strings or streams, allowing seamless processing of different encodings.

Question 4

Can I integrate sedlex with Menhir's incremental API?

Accepted Answer

Yes, sedlex integrates with Menhir's incremental API using Sedlexing.with_tokenizer to supply tokens directly, as demonstrated in the examples directory, though it requires careful setup.

Question 5

What are the performance implications of using sedlex on large text files?

Accepted Answer

sedlex may be slower than ocamllex due to Unicode processing overhead, especially for large files with simple encodings. Optimize by using efficient regex patterns and avoiding unnecessary captures.

Question 6

How to handle lexing errors or unexpected characters in sedlex?

Accepted Answer

Define a catch-all rule with 'any' to consume and report unexpected characters, using Sedlexing.Utf8.lexeme to extract the lexeme. Avoid using '_' as it doesn't consume input.

Sedlex

What is Sedlex?

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