https://github.com/alexknauth/struct-like-struct-type-property

Creating struct-type properties with a struct-like interface
https://github.com/alexknauth/struct-like-struct-type-property

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Creating struct-type properties with a struct-like interface

• Host: GitHub
• URL: https://github.com/alexknauth/struct-like-struct-type-property
• Owner: AlexKnauth
• License: mit
• Created: 2018-06-05T19:54:54.000Z (over 6 years ago)
• Default Branch: main
• Last Pushed: 2022-01-07T14:24:50.000Z (almost 3 years ago)
• Last Synced: 2024-10-16T02:55:19.985Z (3 months ago)
• Language: Racket
• Size: 13.7 KB
• Stars: 5
• Watchers: 4
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE.txt

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README

        
# struct-like-struct-type-property

Creating struct-type properties with a struct-like interface.

[_Documentation_](https://docs.racket-lang.org/struct-like-struct-type-property/index.html).

```racket

(require struct-like-struct-type-property)

```

```racket

(define-struct-like-struct-type-property name [field ...]

  prop-option ...)

  

  prop-option = #:property prop-expr val-expr

```

Defines these identifiers:

 - `prop:name`

 - `name`

 - `name?`

 - `name-field` ...

 

The property `prop:name` expects a function that takes a

"self" argument and returns a `name` result. When someone

wants to use the value as a `prop:name`, this function

should construct a more basic structure that contains the

field values.

Example:

```racket

(define-struct-like-struct-type-property foo [a b c])

> (foo-a (foo 1 2 3))

1

> (foo? (foo "a" "b" "c"))

#true

> (struct bar [x]

    #:property prop:foo

    (lambda (self)

      (foo (first (bar-x self))

           (second (bar-x self))

           (third (bar-x self)))))

> (foo-a (bar (list 4 5 6)))

4

> (foo? (bar (list 'd 'e 'f)))

#true

> (match (bar (list 1 3 5))

    [(foo a b c) c])

5

```

The `#:property prop-expr val-expr` options specify

super-properties. Anything that implements `prop:name` will

automatically implement all the properties specified by the

given `prop-exprs`.

Example:

```racket

(define-struct-like-struct-type-property quadratic [a b c]

  #:property prop:procedure

  (λ (self x)

    (+ (* (quadratic-a self) (sqr x))

       (* (quadratic-b self) x)

       (quadratic-c self))))

> (define f (quadratic 1 -2 -3))

> (f 0)

-3

> (f 1)

-4

> (f 2)

-3

> (f 3)

0

> (f 4)

5

```