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

equals (x) (eval (show (x)))
https://github.com/sanctuary-js/sanctuary-show

sanctuary

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equals (x) (eval (show (x)))

• Host: GitHub
• URL: https://github.com/sanctuary-js/sanctuary-show
• Owner: sanctuary-js
• License: mit
• Created: 2018-04-11T10:14:18.000Z (over 6 years ago)
• Default Branch: main
• Last Pushed: 2024-01-25T16:14:23.000Z (11 months ago)
• Last Synced: 2024-04-28T18:04:36.993Z (8 months ago)
• Topics: sanctuary
• Language: JavaScript
• Size: 58.6 KB
• Stars: 14
• Watchers: 10
• Forks: 5
• Open Issues: 2
• Metadata Files:
  • Readme: README.md
  • Contributing: .github/CONTRIBUTING.md
  • Funding: .github/FUNDING.yml
  • License: LICENSE

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README

        
# sanctuary-show

Haskell has a `show` function which can be applied to a compatible value to

produce a descriptive string representation of that value. The idea is that

the string representation should, if possible, be an expression which would

produce the original value if evaluated.

This library provides a similar [`show`](#show) function.

In general, this property should hold: `eval (show (x)) = x`. In some cases

parens are necessary to ensure correct interpretation (`{}`, for example,

is an empty block rather than an empty object in some contexts). Thus the

property is more accurately stated `eval ('(' + show (x) + ')') = x`.

One can make values of a custom type compatible with [`show`](#show) by

defining a `@@show` method. For example:

```javascript

//# Maybe#@@show :: Maybe a ~> () -> String

//.

//. ```javascript

//. > show (Nothing)

//. 'Nothing'

//.

//. > show (Just (['foo', 'bar', 'baz']))

//. 'Just (["foo", "bar", "baz"])'

//. ```

Maybe.prototype['@@show'] = function() {

  return this.isNothing ? 'Nothing' : 'Just (' + show (this.value) + ')';

};

```

### `show :: Showable a => a -⁠> String`

Returns a useful string representation of the given value.

Dispatches to the value's `@@show` method if present.

Where practical, `show (eval ('(' + show (x) + ')')) = show (x)`.

```javascript

> show (null)

'null'

> show (undefined)

'undefined'

> show (true)

'true'

> show (new Boolean (false))

'new Boolean (false)'

> show (-0)

'-0'

> show (NaN)

'NaN'

> show (new Number (Infinity))

'new Number (Infinity)'

> show ('foo\n"bar"\nbaz\n')

'"foo\\n\\"bar\\"\\nbaz\\n"'

> show (new String (''))

'new String ("")'

> show (['foo', 'bar', 'baz'])

'["foo", "bar", "baz"]'

> show ([[[[[0]]]]])

'[[[[[0]]]]]'

> show ({x: [1, 2], y: [3, 4], z: [5, 6]})

'{"x": [1, 2], "y": [3, 4], "z": [5, 6]}'

```