minikanren

1.0.5 · active · verified Sat Apr 11

minikanren is a Python library that provides a Domain Specific Language (DSL) for relational (logic) programming. It enables users to express sophisticated relations—in the form of goals—and generate values that satisfy these relations. The library is often used as an algorithmic core for Computer Algebra Systems and for the automated generation and optimization of numeric software. The current version is 1.0.5, with ongoing development and participation in miniKanren workshops across various language implementations. [2, 3]

Warnings

gotcha The PyPI package is `minikanren`, but the Python module to import is `kanren`. Importing from `minikanren` directly will result in an `ImportError`. [2, 3]
Fix: Always use `from kanren import ...` for imports.
gotcha Like other logic programming languages, `minikanren` queries may enter an infinite loop if no solution exists within an infinite search tree. The interleaved search strategy guarantees finding solutions if they exist, but cannot guarantee termination if no solution is found and the search space is unbounded. [16]
Fix: Carefully design goals to constrain the search space or be aware of potential non-termination for certain queries.
gotcha While `minikanren`'s interleaving search provides completeness, the order of goals can still impact performance, especially in complex scenarios. Inefficient goal ordering might lead to longer execution times or seemingly non-terminating searches if favorable branches are explored later. [18, 20]
Fix: Experiment with different goal orderings, prioritizing more restrictive goals earlier in conjunctions (`lall`) to prune the search space faster.
breaking The `kanren` project is a fork of `logpy` and while aiming for syntactic parity, it deviates significantly in 'core mechanics and offerings'. Users migrating from `logpy` should be aware that internal behaviors and potential extensions might differ substantially. [2]
Fix: Consult `minikanren` documentation and examples when migrating from `logpy` to understand the differences in core implementation and available features.

Install

pip install minikanren Install with pip

Imports

run, eq, membero, var, lall
```
from kanren import run, eq, membero, var, lall
```
The PyPI package name is `minikanren`, but the Python importable package is `kanren`.

Quickstart

This quickstart demonstrates basic relational programming with `minikanren`. It shows how to declare logic variables (`var`), express equality relations (`eq`), and run a query to find solutions. The first example finds `x` such that `x` equals 5. The second finds `y` and `z` such that both are 3. The third shows unification of a structure. [2, 3]

from kanren import run, eq, var

x = var()
results = run(1, x, eq(x, 5))
print(results)

y, z = var(), var()
results_multi = run(1, (y, z), eq(y, z), eq(z, 3))
print(results_multi)

# Example with unification of structures
results_struct = run(1, x, eq((1, 2), (1, x)))
print(results_struct)

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