ibis-typing

A typed framework for writing Ibis dataframe expressions — with full IDE support, static analysis, and property-based testing.

Ibis is a portable Python dataframe library (DSL) that runs on DuckDB, Polars, Trino, BigQuery, and more. ibis-typing layers a type-safe schema system on top of it, so your transforms carry type information end-to-end.

Installation

pip install ibis-typing

uv add ibis-typing

After installation, run the type-patch step once to inject typed overloads into your installed ibis package:

python -m ibis_typing.type_patch

Quick start

1. Define schemas

from attrs import frozen
from ibis_typing import IbisSchema, it

@frozen
class Transaction(IbisSchema):
    date: it.Date = None
    amount: it.Float64 = None
    category: it.String = None

2. Define a typed expression

from ibis_typing import Expression, IbisTable, this, it

@frozen
class MonthlyAmounts(Expression):
    month: it.Date = None
    amount: it.Float64 = None

    @classmethod
    def from_expression(cls, inputs: IbisTable[Transaction]):
        cols = inputs.cols
        table = (
            inputs.table
            @ it.Select(expr={"month": this[cols.date].truncate("M")})
            @ it.Aggregate(by=["month"], sum=[cols.amount])
        )
        return cls.of(table)

Tip: IbisSchema classes for your Expression outputs can be generated automatically using ibis_typing.schema_writer. The code is backend-agnostic — schemas are derived from abstract Ibis table schemas, so no live backend is required.

3. Evaluate against a backend

from datetime import date

from ibis_typing import IbisConnection, evaluator

conn = IbisConnection()
transactions = Transaction.of_rows([Transaction(date=date(2024, 1, 15), amount=100.0, category="A")])
monthly_amounts = evaluator.from_expression(MonthlyAmounts, transactions)
results: list[MonthlyAmounts] = list(conn.fetch_table(monthly_amounts))

4. Test with Hypothesis

pytest fixtures are registered automatically — no conftest.py needed.

from hypothesis import given, strategies as st
from ibis_typing.hypothesis import strategy_for

@given(st.lists(strategy_for(Transaction), min_size=1))
def test_monthly_amounts(evaluate_table, transactions):
    actual, expected = evaluate_table(MonthlyAmounts, transactions)
    assert sorted(actual) == sorted(expected)

Core concepts

graph TD
    IbisSchema -->|describes| IbisTable
    IbisTable -->|In| Expression
    Expression -->|Out| IbisTable
    TableProvider -->|provides tables to| Expression
    IbisConnection -->|fetches typed rows from| IbisTable
    ChecksumBuckets -->|incremental inputs to| IncrementalExpression
    IncrementalExpression -->|is a| Expression
    BucketedInputsExpression -->|is a| IncrementalExpression
    RevertibleTableExpression -->|can revert| Expression

Loading

Class	Purpose
IbisSchema	Base class for typed table schemas (attrs frozen dataclass)
IbisTable[S]	Generic typed wrapper around ibis.Table
Expression	Abstract base for typed ibis transforms
IbisConnection	Typed backend wrapper: fetch_table(), evaluate(), read/write_parquet()
BucketedInputsExpression	Expression that only re-runs for changed input buckets
ChecksumBuckets	Checksum-based incremental input tracking
RevertibleTableExpression	Transform that can undo itself back to the original schema

Type aliases

Declare schema fields using column-type aliases from ibis_typing.it:

from ibis_typing import it

it.Int8, it.Int16, it.Int32, it.Int64
it.Float32, it.Float64
it.Boolean
it.String, it.Binary
it.Decimal
it.Date, it.Time, it.Timestamp
it.UUID, it.JSON
it.Array[it.Int64]
it.Map[it.String, it.Float64]
it.Struct[MyTypedDict]

Table operations

Use the infix @ operator for composable, typed table transforms:

from ibis_typing import IbisSchema, IbisTable, this, it

@frozen
class InputSchema(IbisSchema):
    a: it.Float64 = None
    b: it.Float64 = None
    category: it.String = None
    amount: it.Float64 = None
    key: it.String = None


inputs: IbisTable[InputSchema] = ...
other_table: IbisTable = ...
cols = InputSchema.cols

table = InputSchema.of(
    inputs.table
    @ it.Select(cols.a, cols.b, expr={"c": this[cols.a] + this[cols.b]})
    @ it.Aggregate(by=[cols.category], sum=[cols.amount])
    @ it.InnerJoin(other_table.table, keys=[cols.key])
)

Pytest fixtures

The following fixtures are auto-registered via the pytest plugin entry point (no conftest.py needed):

Fixture	Purpose
evaluate_table	Runs an Expression, returns (actual, expected) row lists
fetch_table	Fetches rows from an IbisTable via DuckDB
ibis_connection	Provides a DuckDB-backed IbisConnection

Extras

• ibis_typing.type_patch — patches installed ibis with typed @overload stubs for ibis.ifelse, ibis.cases, ibis.coalesce, etc.
• ibis_typing.schema_writer — code-gen: write IbisSchema .py files from Expression output schemas
• ibis_typing.plot — plots the dependency graph of an Expression using matplotlib/graphviz
• ibis_typing.custom — custom ibis operations: DateAddMonth, DateAddDay, ColumnChecksum, JsonParse, JsonFormat, UUIDFromInt, LuhnCheck

Contributing

git clone https://github.com/FortnoxAB/ibis-typing
cd ibis-typing
uv sync --all-extras
uv run python -m ibis_typing.type_patch
make test

Pull requests welcome. Please run make before submitting.

License

MIT