Hakyll.Web.Template.Context

Mostly for internal usage

The Context monoid. Please note that the order in which you compose the items is important. For example in

field "A" f1 <> field "A" f2

the first context will overwrite the second. This is especially important when something is being composed with metadataField (or defaultContext). If you want your context to be overwritten by the metadata fields, compose it from the right:

metadataField <> field "date" fDate

Constructs a new field for a Context. If the key matches, the compiler is run and its result is substituted in the template.

If the compiler fails, the field will be considered non-existent in an $if()$ macro or ultimately break the template application (unless the key is found in another context when using <>). Use empty or noResult for intentional failures of fields used in $if()$, to distinguish them from exceptions thrown with fail.

Creates a field to use with the $if()$ template macro. Attempting to substitute the field into the template will cause an error.

Creates a field to use with the $if()$ template macro, in the Compiler monad. Attempting to substitute the field into the template will cause an error.

Creates a field that does not depend on the Item but always yields the same string

Creates a list field to be consumed by a $for(…)$ expression. The compiler returns multiple items which are rendered in the loop body with the supplied context.

Creates a list field like listField, but supplies the current page to the compiler.

Creates a variadic function field.

The function will be called with the dynamically evaluated string arguments from the template as well as the page that is currently rendered.

Transform the respective string results of all fields in a context. For example,

mapContext (++"c") (constField "x" "a" <> constField "y" "b")

is equivalent to

constField "x" "ac" <> constField "y" "bc"

Transform the respective string results of all fields in a context satisfying a predicate. For example,

mapContextBy (=="y") (++"c") (constField "x" "a" <> constField "y" "b")

is equivalent to

constField "x" "a" <> constField "y" "bc"

A context that contains (in that order)

1. A $body$ bodyField

2. Metadata fields

3. A $url$ urlField

4. A $path$ pathField

5. A $title$ titleField

This order means that all of the fields, except $body$, can have their values replaced by metadata fields of the same name. For example, a context from a file at posts/foo.markdown has a default title foo. However, with a metadata field:

---
title: The Foo Story
---

The $title$ will be replaced with The Foo Story.

Body of the item, that is, the main content of the underlying file

Map any field to its metadata value, if present

Absolute url to the resulting item. For an example item that produces a file posts/foo.html, this field contains "posts/foo.html"

Filepath of the underlying file of the item. For an example underlying file posts/foo.markdown, this field contains "posts/foo.markdown"

Basename of the underlying file of the item. For an example underlying file posts/foo.markdown, this field contains "foo"

A context that allows snippet inclusion. In processed file, use as:

...
$snippet("path/to/snippet/")$
...

The contents of the included file will not be interpolated like partial does it.

When the metadata has a field called published in one of the following formats then this function can render the date.

• Mon, 06 Sep 2010 00:01:00 +0000

• Mon, 06 Sep 2010 00:01:00 UTC

• Mon, 06 Sep 2010 00:01:00

• 2010-09-06T00:01:00+0000

• 2010-09-06T00:01:00Z

• 2010-09-06T00:01:00

• 2010-09-06 00:01:00+0000

• 2010-09-06 00:01:00

• September 06, 2010 00:01 AM

Following date-only formats are supported too (00:00:00 for time is assumed)

• 2010-09-06

• 06.09.2010

• September 06, 2010

Alternatively, when the metadata has a field called path in a folder/yyyy-mm-dd-title.extension format (the convention for pages) and no published metadata field set, this function can render the date. This pattern matches the file name or directory names that begins with yyyy-mm-dd . For example: folder/yyyy-mm-dd-titledist/main.extension . In case of multiple matches, the rightmost one is used.

As another alternative, if none of the above matches, and the file has a path which contains nested directories specifying a date, then that date will be used. In other words, if the path is of the form **/yyyymmdd/main.extension . As above, in case of multiple matches, the rightmost one is used.

This is an extended version of dateField that allows you to specify a time locale that is used for outputting the date. For more details, see dateField and formatTime.

Parser to try to extract and parse the time from the published field or from the filename. See dateField for more information. Exported for user convenience.

Get the time on which the actual file was last modified. This only works if there actually is an underlying file, of couse.

Creates a field with the last modification date of the underlying item.

Creates a field with the last modification date of the underlying item in a custom localisation format (see formatTime).

A context with "teaser" key which contain a teaser of the item. The item is loaded from the given snapshot (which should be saved in the user code before any templates are applied).

A context with "teaser" key which contain a teaser of the item, defined as the snapshot content before the teaser separator. The item is loaded from the given snapshot (which should be saved in the user code before any templates are applied).

Constantly reports any field as missing. Mostly for internal usage, it is the last choice in every context used in a template application.