# Haskell QuickCheck

This note covers `26-haskell-quickcheck/`, which normalizes overlapping maintenance windows and checks the implementation with QuickCheck
properties.

---

## 1. Why Properties Help Here

The function under test is not a single arithmetic helper. It sorts, merges, and preserves the covered time range of several windows.

That kind of behavior is a strong fit for property testing, because you care about broad rules:

- the result should be normalized,
- normalizing twice should not change the answer, and
- the normalized result should cover exactly the same minutes as the input.

Those are better teaching examples for QuickCheck than a one-line `reverse . reverse` property.

---

## 2. What the Generator Controls

The test suite generates windows within a bounded minute range.

That keeps the coverage property finite, because the test can compare membership across `0..60` directly.

The important point is not the numeric range itself. It is the workflow:

1. generate realistic structured input,
2. state invariant-like properties, and
3. let QuickCheck search for counterexamples.

---

## 3. Commands to Try

```bash
cd 26-haskell-quickcheck

nix develop
cabal run
cabal run -- 0-10 8-14 20-24 24-30
cabal test

nix build
./result/bin/mini-windows 0-10 8-14 20-24 24-30

nix run . -- 0-10 8-14 20-24 24-30
nix flake check
```