https://github.com/sanctuary-js/sanctuary-useless

Data type with no functionality (useful for testing)
https://github.com/sanctuary-js/sanctuary-useless

sanctuary

Last synced: about 2 months ago
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Data type with no functionality (useful for testing)

• Host: GitHub
• URL: https://github.com/sanctuary-js/sanctuary-useless
• Owner: sanctuary-js
• License: mit
• Created: 2018-05-06T16:46:14.000Z (over 6 years ago)
• Default Branch: main
• Last Pushed: 2024-10-27T12:07:46.000Z (2 months ago)
• Last Synced: 2024-10-28T15:22:10.577Z (2 months ago)
• Topics: sanctuary
• Language: JavaScript
• Homepage:
• Size: 74.2 KB
• Stars: 5
• Watchers: 10
• Forks: 1
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • Contributing: .github/CONTRIBUTING.md
  • Funding: .github/FUNDING.yml
  • License: LICENSE

Awesome Lists containing this project

README

        
# sanctuary-useless

This package exports a single value, `Useless`, the sole member of the

sanctuary-useless/Useless type:

```javascript

//    Useless :: Useless

const Useless = require ('sanctuary-useless');

```

`Useless`, as its name suggests, has no functionality. This makes it useful

for testing algebraic data types which satisfy various [type classes][].

The following assertion, in isolation, suggests that `Identity a` satisfies

[`Z.Setoid`][] _for all_ `a`:

```javascript

eq (Z.Setoid.test (Identity (0))) (true);

```

`Identity Useless`, though, does not satisfy `Z.Setoid`, indicating that

`a` is constrained in some way:

```javascript

eq (Z.Setoid.test (Identity (Useless))) (false);

eq (Z.Setoid.test (Identity (0))) (true);

```

Conversely, one can use `Useless` to demonstrate universal quantification

where applicable:

```javascript

eq (Z.Functor.test (Identity (Useless))) (true);

```

[`Z.Setoid`]:       https://github.com/sanctuary-js/sanctuary-type-classes/tree/v12.1.0#Setoid

[type classes]:     https://github.com/sanctuary-js/sanctuary-type-classes/tree/v12.1.0