Collections

Operating on lists and maps — head, tail, append, distinct, sort.

Function	Arity	What
`len`	1	Length of a list / map / string
`isEmpty`	1	True iff the collection has zero items
`nonEmpty`	1	True iff the collection has at least one item
`head`	1	First element of a list
`tail`	1	All but the first
`first`	1	Alias for `head`
`last`	1	Last element
`reverse`	1	Reversed copy
`sort`	1	Sorted copy (natural ordering on the elements)
`distinct`	1	Drop duplicates, preserving original order
`compact`	1	Drop `null` and the empty-tuple `()` from a list
`append`	2	`append elem list` — append to the right
`prepend`	2	`prepend elem list` — prepend to the left

Examples

{{ .args | head }}                          first positional arg
{{ .args | tail | join ' ' }}               drop first, rejoin

{{ for n <- .nums | distinct | sort }}      unique then sorted
  {{ n }}
{{ end }}

{{ if .items | nonEmpty }}…{{ end }}        guard against empty list

{{ .tags | append 'featured' | join ' ' }}  add a tag, render

Maps

for k, v <- m iterates a map. Many of the list builtins above work on maps too — len m returns the entry count, isEmpty m checks for an empty map.

To pluck a value by key, use […] indexing in expressions:

{{ .config['baseURL'] }}
{{ .frontmatter.tags }}        // dot syntax works for string keys