README.md


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yants
=====

[![Build Status](https://travis-ci.org/tazjin/yants.svg?branch=master)](https://travis-ci.org/tazjin/yants)

This is a tiny type-checker for data in Nix, written in Nix.

Features:

* Checking of primitive types (`int`, `string` etc.)
* Checking polymorphic types (`option`, `list`, `either`)
* Defining & checking struct/record types
* Defining & matching enum types
* Defining & matching sum types
* Defining function signatures (including curried functions)
* Types are composable! `option string`! `list (either int (option float))`!
* Type errors also compose!

Lacking:

* Any kind of inference
* Convenient syntax for attribute-set function signatures

## Primitives & simple polymorphism

![simple](screenshots/simple.png)

## Structs

![structs](screenshots/structs.png)

## Nested structs!

![nested structs](screenshots/nested-structs.png)

## Enums!

![enums](screenshots/enums.png)

## Functions!

![functions](screenshots/functions.png)