FOLint

FOLint is a linting tool for FO(·). Its functionality can be split up in four parts:

• Detection of syntax errors
• Detection of type errors
• Detection of typical formalization errors
• Enforcing a style guide

This project was initially started by Lars Vermeulen during his master thesis: https://github.com/larsver/folint

Installation

pip install folint

CLI usage

folint file.idp

FOLint in editors

FOLint can be integrated in many editors. A collection of guides are kept in the folint-in-editors folder.

Build new version

python setup.py bdist_wheel sdist

Don't forget to update the version number of FOLint + the version number of IDP in the dependency!

Appendix: Full list of functionality

For a full list, see "Vermeulen, L. (2022). Statische Code Analyse voor FO(·). KU Leuven. Faculteit Industriële Ingenieurswetenschappen."

Type Checking

• Typing of comparisons (f = g, f > g, …)
• Typing of mathematical operators (x + y, x - y, …)
• Warning for untyped quantifiers
• Verifying the types of the elements in symbol interpretations

Common mistake checking

• Warning when using a conjunction with universal quantification (e.g., !x in Person: age(x) > 18 & adult(x))
• Warning when using an implication with existential quantification (e.g., ?x in Person: driving_license(x) => sober(x))
• Worning when variable is only on one side of an equivalence (e.g., !x,y: phi(x) <=> psi(x, y))

Style guide

• Use brackets with negated in statement
• Warn against redundant brackets
• Naming conventions: Type starting with capital letter, other symbols in snake_case
• Highlight unused quantification variables
• Warn when not using pretty_print

Other

• Wrong number of arguments for predicate/function
• Wrong number of arguments for model_check or using unknown block names
• Checking if types are defined in voc or struct
• Checking totality of functions
• Checking for duplicate entries in interpretations
• Checking corretness of entries in interpretations
• Other minor linting such as "no double spaces", "spaces around connectives", ...