sql

SQL Lambda Core

This implementation uses SQLite to demonstrate the Lambda Core through a relational emulation. SQLite does not have first-class functions, so Church booleans are stored by the argument branch they select, while a Church numeral is stored as one row per function application. Views implement NOT, AND, and OR; triggers implement reusable SUCC and PRED transformations.

Requirements

• SQLite 3
• No extensions or external packages

SQLite is included in GitHub's current ubuntu-latest runner image, so this folder does not require a workflow installation step.

Run and verify

From this directory, run:

sh test.sh

The script evaluates lambda-core.sql in a fresh in-memory database. Each example is inserted into a table whose CHECK constraint compares actual and expected values, so an incorrect operation exits nonzero before output. The repository-level run-tests.sh compares the observed output with expected-output.txt.

Why this is an emulation

The project explicitly permits languages to express or emulate the core lambda-calculus concepts. SQL's reusable abstraction is a relation rather than a closure. The implementation preserves Church behavior—the boolean selects one branch, and a numeral describes repeated application—without claiming that SQLite rows are first-class lambda terms.

The implementation relies only on SQLite's documented CREATE TRIGGER behavior.