v0.7.0

Python CEL 0.7.0 gives you a much bigger built-in toolbox, lets you call your own functions as methods, and can tell you what an expression uses before you run it — on top of a refreshed, more secure Rust core.

✨ What's new

An extended standard library — dozens of functions matching Google's cel-go, opt-in via cel.stdlib:

import cel
from cel.stdlib import add_stdlib_to_context

ctx = cel.Context()
add_stdlib_to_context(ctx)

cel.evaluate('"Hello World".lowerAscii()', ctx)   # 'hello world'
cel.evaluate("math.greatest([3, 1, 2])", ctx)     # 3
cel.evaluate("[1, 1, 2, 3].distinct()", ctx)      # [1, 2, 3]
cel.evaluate('base64.encode(b"hi")', ctx)         # 'aGk='

Covers strings, math, sets, encoders and lists helpers (plus bool/dyn/type/min/max). The cel command-line tool enables them automatically.

Call custom functions as methods — a function you register works as both f(x) and x.f(y):

ctx = cel.Context()
ctx.add_function("shout", lambda s: s.upper() + "!")
cel.evaluate('"hi".shout()', ctx)   # 'HI!'

Inspect an expression before running it — see which variables and functions it references:

program = cel.compile("user.age >= min_age && size(roles) > 0")
program.variables()   # ['min_age', 'roles', 'user']
program.functions()   # ['_&&_', '_>=_', '_>_', 'size']

Handy for validating that your context supplies everything an expression needs, or restricting which names an expression may touch.

⚡ Under the hood

• Upgraded to cel-rust 0.14 — faster and more spec-compliant.
• Upgraded to PyO3 0.29, which pulls in upstream security fixes.
• Clearer, more Pythonic error messages (e.g. TypeError: Unsupported operation: string + int).

⚠️ Heads up — behaviour changes

These come from cel 0.14 and may affect existing expressions:

• contains is now string-only. Use the in operator for membership — 2 in [1, 2, 3], "key" in myMap — or enable the lists extension to get .contains() back for lists and maps.
• min/max moved into the opt-in cel.stdlib core extension (they used to be always available).
• Built-in functions take precedence over a custom function registered with the same name.

📦 Install / upgrade

pip install --upgrade common-expression-language

See the CHANGELOG for the complete list of changes, and the docs for the new standard-library and introspection reference.

v0.5.6

What's Changed

• Fix mapping conversion for dict subclasses by @hardbyte in #29

Full Changelog: v0.5.5...v0.5.6

v0.5.5

Highlights

• Upgrade to cel‑rust 0.12.0 (bytes feature enabled)
• New compile() API + Program.execute() for fast repeated evaluation
• New OptionalValue wrapper to represent CEL optional values in Python (preserves optional.none() vs optional.of(null))

Added

• Compile/execute performance benchmark: examples/performance/compile_execute_benchmark.py
• OptionalValue docs and examples

Notes

• Optional values now surface as cel.OptionalValue instead of debug strings.
• Performance guidance updated with compile/execute examples.

New Contributors

• @shlee322 made their first contribution in #27

Full Changelog: v0.5.3...v0.5.5

v0.5.3: Add substring() function to stdlib and improve logging (#21)

• Added stdlib in Python to add functions before they land upstream. Added substring
• removed warning level logging in cel crate

v0.5.1

✨ Added

• EvaluationMode enum: Control type handling behavior in CEL expressions
  • EvaluationMode.PYTHON (default for Python API): Python-friendly type promotions
  • EvaluationMode.STRICT (default for CLI): Strict CEL type rules with no coercion
• Type checking support: Added complete type stub files (.pyi) for PyO3 extension

v0.5.0: Release/0.5.0 (#8)

🚨 Breaking Changes (Rust API only)

• Upgraded cel crate (formerly cel-interpreter) 0.10.0 → 0.11.0:
  • Function registration now uses IntoFunction trait.
  • Python integration updated to use Arguments extractor for variadic args.
  • Imports renamed from cel_interpreter:: to cel::.
  • No changes to Python API – all existing code continues to work.

✨ Changed

• Internal: Refactored Python integration to match new CEL API.
• Updated dependencies:
  • pyo3: 0.25.0 → 0.25.1
  • pyo3-log: 0.12.1 → 0.12.4

🗒 Maintainer Notes

• Prepared for upcoming CEL Rust features:
  • Enhanced type system & introspection
  • type() function support
  • Optional value handling

v0.4.1

Pygments Warning in CLI Fixed

CLI REPL syntax highlighting now works without warnings

v0.4.0

🚀 CLI Interface

• Command-line tool: cel command now available after installation
• Interactive REPL: Enhanced terminal experience with syntax highlighting, auto-completion, and command history
• Multiple output formats: JSON, pretty tables, Python repr, and auto-detection
• File processing: Batch evaluation of expressions from files
• Context loading: JSON context files for complex evaluations

Command-line usage

$ cel '1 + 2'                           # → 3
$ cel --interactive                     # Launch REPL
$ cel 'age >= 21' --context user.json  # Context from file

🧪 Testing

• 200+ tests: Complete coverage of all CEL features and edge cases
• 35 new CLI tests: Formatter, REPL, file operations, and integration testing
• Performance verification: Microsecond-level evaluation benchmarks
• Error handling tests: Parser errors, type errors, and edge cases

🔧 Technical Improvements

CEL Interpreter Update

• cel-interpreter: 0.9.0 → 0.10.0 (enhanced CEL specification compliance)

PyO3 0.25.0 Migration

• Modern API: Migrated from deprecated IntoPy to IntoPyObject<'py> trait
• Better error handling: Improved type conversion with proper lifetime management
• Enhanced type safety: New conversion system with comprehensive error propagation
• Graceful degradation: Parser panics converted to proper PyValueError exceptions

Documentation

• Comprehensive Python-facing documentation with examples and type hints
• Context class: Detailed docstrings for all methods with usage examples

📦 Dependencies

• pyo3: 0.22.6 → 0.25.0
• cel-interpreter: 0.9.0 → 0.10.0
• log: 0.4.22 → 0.4.27
• chrono: 0.4.38 → 0.4.41
• pyo3-log: 0.11.0 → 0.12.1

Full Changelog: v0.3.1...v0.4.0

v0.3.1

Bug fix - support None values

v0.3.0

Adds supports for CEL expressions to use user defined Python Functions.

from cel import evaluate

def is_adult(age):
    return age > 21

evaluate("is_adult(age)", {'is_adult': is_adult, 'age': 18})
# False

Also updates pyo3 and cel-interpreter to latest stable versions.