docs: Document built-in functions

docs/kiln.1.scd

@@ -266,6 +266,68 @@ Templates have certain data and functions available to them.
 
 All templates have the following functions available to them:
 
+*and* _args..._
+	Returns the boolean AND of its arguments by returning the
+	first empty argument or the last argument, that is,
+	"and x y" behaves as "if x then y else x". All the
+	arguments are evaluated.
+
+*call* _function_, _args..._
+	Returns the result of calling the first argument, which
+	must be a function, with the remaining arguments as parameters.
+	Thus "call .X.Y 1 2" is, in Go notation, dot.X.Y(1, 2) where
+	Y is a func-valued field, map entry, or the like.
+	The first argument must be the result of an evaluation
+	that yields a value of function type (as distinct from
+	a predefined function such as print). The function must
+	return either one or two result values, the second of which
+	is of type error. If the arguments don't match the function
+	or the returned error value is non-nil, execution stops.
+
+*eq* _arg1_, _arg2_
+	Returns the boolean truth of _arg1_ == _arg2_.
+
+*ge* _arg1_, _arg2_
+	Returns the boolean truth of _arg1_ >= _arg2_.
+
+*gt* _arg1_, _arg2_
+	Returns the boolean truth of _arg1_ > _arg2_.
+
+*html* _args..._
+	Returns the escaped HTML equivalent of the textual
+	representation of its arguments. This function is unavailable
+	in HTML templates, with a few exceptions.
+
+*index* _collection_, _args..._
+	Returns the result of indexing its first argument by the
+	following arguments. Thus "index x 1 2 3" is, in Go syntax,
+	x[1][2][3]. Each indexed item must be a map, slice, or array.
+
+*js* _args..._
+	Returns the escaped JavaScript equivalent of the textual
+	representation of its arguments.
+
+*le* _arg1_, _arg2_
+	Returns the boolean truth of _arg1_ <= _arg2_.
+
+*len* _list_
+	Returns the integer length of its argument.
+
+*lt* _arg1_, _arg2_
+	Returns the boolean truth of _arg1_ < _arg2_.
+
+*ne* _arg1_, _arg2_
+	Returns the boolean truth of _arg1_ != _arg2_.
+
+*not* _arg_
+	Returns the boolean negation of its single argument.
+
+*or* _args..._
+	Returns the boolean OR of its arguments by returning the
+	first non-empty argument or the last argument, that is,
+	"or x y" behaves as "if x then x else y". All the
+	arguments are evaluated.
+
 *path.Base* _path_
 	Returns the last element of _path_.
 
@@ -281,6 +343,17 @@ All templates have the following functions available to them:
 *path.Join* _elem..._
 	Joins any number of path elements into a single path.
 
+*print* _args..._
+	Formats using the default formats for its operands and returns the resulting
+	string. Spaces are added between operands when neither is a string.
+
+*printf* _format_, _args..._
+	Formats according to a format specifier and returns the resulting string.
+
+*println* _args..._
+	Formats using the default formats for its operands and returns the resulting
+	string. Spaces are always added between operands and a newline is appended.
+
 *reverse* _list_
 	Returns a reversed copy of the provided slice or array.
 
@@ -302,6 +375,12 @@ All templates have the following functions available to them:
 *site*
 	Returns site metadata (see *SITE METADATA*).
 
+*slice* _list_, _args..._
+	slice returns the result of slicing its first argument by the
+	remaining arguments. Thus "slice x 1 2" is, in Go syntax, x[1:2],
+	while "slice x" is x[:], "slice x 1" is x[1:], and "slice x 1 2 3"
+	is x[1:2:3]. The first argument must be a string, slice, or array.
+
 *strings.Count* _string_, _substr_
 	Counts the number of non-overlapping instances of _substr_ in _string_.
 	If _substr_ is an empty string, Count returns 1 + the number of Unicode code
@@ -388,6 +467,12 @@ All templates have the following functions available to them:
 	Returns _string_ without the provided trailing _suffix_ string. If _string_
 	doesn't end with _suffix_, it is returned unchanged.
 
+*urlquery* _args..._
+	Returns the escaped value of the textual representation of
+	its arguments in a form suitable for embedding in a URL query.
+	This function is unavailable in HTML templates, with a few
+	exceptions.
+
 ## SITE METADATA
 
 Site metadata contains the following data: