►Pollen:   the book is a program
▼9 Module reference
9.1 Cache
9.2 Decode
9.3 File
9.4 Pagetree
9.5 Render
9.6 Template
9.7 Tag
9.8 Top
9.9 World
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make-tag-function
6.0.1
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9.7 Tag

 (require pollen/tag) package: pollen

Convenience functions for working with tags.

procedure

(make-tag-function id) → (-> txexpr?)

  id : txexpr-tag?
Make a tag function for id. As arguments, a tag function takes an optional set of X-expression attributes (txexpr-attrs?) followed by X-expression elements (txexpr-elements?). From these, the tag function creates a tagged X-expression using id as the tag.

Examples:

> (require pollen/tag)
> (define beaucoup (make-tag-function 'em))
> (beaucoup "Bonjour")

'(em "Bonjour")

> (beaucoup '((id "greeting")) "Bonjour")

'(em ((id "greeting")) "Bonjour")

Entering attributes this way can be cumbersome. So for convenience, a tag function provides an alternative: any symbol + string pairs at the front of your expression will be interpreted as attributes, if the symbols are followed by a colon. If you leave out the colon, the symbols will be interpreted as part of the content of the tag.

Examples:

> (require pollen/tag)
> (define beaucoup (make-tag-function 'em))
> (beaucoup 'id: "greeting" 'class: "large" "Bonjour")

'(em ((id "greeting") (class "large")) "Bonjour")

; Don't forget the colons
> (beaucoup 'id "greeting" 'class "large" "Bonjour")

'(em id "greeting" class "large" "Bonjour")

; Don't forget to provide a value for each attribute
> (beaucoup 'id: 'class: "large" "Bonjour")

'(em id: class: "large" "Bonjour")

Pollen also uses this function to provide the default behavior for undefined tags. See #%top.

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