LangCode 2027 Task 1 Data

Data

What you get, how the data is built, and the starter kit.

Updates
Oct 30, 2026Training and development data release; CodaBench registration opens Jan 15, 2027Test data release / evaluation begins Jan 24, 2027Registration deadline Jan 31, 2027System submission deadline Feb 3, 2027Official results released Feb 15, 2027Shared-task paper submission deadline Mar 26, 2027Notification of acceptance Apr 16, 2027Camera-ready paper due Jun 1–5, 2027Workshop at NAACL 2027, San Francisco LangCode 2027Co-located with NAACL 2027 · June 1–5, 2027 · San Francisco, California AlsoShared Task 2: Adversarial Prompt Detection Feb 5, 2027Regular workshop papers due. See the Call for Papers

What you get

Each example is a function signature in one programming language (Python, C, C++, Java, and others) with a problem description in one natural language. Every problem comes with hidden unit tests that decide whether a solution is correct.

SplitPhaseReleasedUse it to
TrainDevelopmentOct 30, 2026Train your system
DevDevelopmentOct 30, 2026Tune your system and practice submitting on CodaBench
TestEvaluationJan 15, 2027Make your final solutions. New problems, hidden tests.

One problem, many languages

The task builds on mHumanEval ↗ (NAACL 2025), a multilingual extension of HumanEval. The same problem is described in more than 100 natural languages, grouped into resource tiers by how much text each language has on the web:

  • High-resource: languages such as English and Spanish.
  • Lower-resource: languages with far less text, where code models struggle most.

The problem also comes in several programming languages, and the solution must be written in the one requested. The correct program does not change with the natural language. The test set uses newly written problems so systems are scored on problems they cannot have memorized.

One problem, many ways to ask for it Natural language
Programming language
def sum_even(nums: list[int]) -> int:
    """
    Return the sum of all even numbers in the list.
    >>> sum_even([1, 2, 3, 4])
    6
    """
    return sum(n for n in nums if n % 2 == 0)
$ run hidden_tests✓ pass

Illustrative problem, not from the test set. Click a tab to pin it.

Starter kit Released Oct 30, 2026

Download it with the data on CodaBench. It gets you from zero to a valid submission.

Train and dev problems

Problems with descriptions across resource tiers, for building and tuning your system.

Public baselines

Baseline results to compare against, so you know where you stand.

Submission format

How to package your solutions in the file format CodaBench accepts.

Download links will appear here on October 30, 2026.

Cite the source benchmark

@inproceedings{raihan2025mhumaneval,
  title     = {m{H}uman{E}val - A Multilingual Benchmark to Evaluate Large Language Models for Code Generation},
  author    = {Raihan, Nishat and Anastasopoulos, Antonios and Zampieri, Marcos},
  booktitle = {Proceedings of NAACL 2025},
  year      = {2025},
  url       = {https://aclanthology.org/2025.naacl-long.570/}
}