Compute functions reference

Every tag in the <compute> sub-language, grouped by what it does. The Compute Language section covers how they fit together.

Reading the signature column: int|str|list means any of the three, … means any number of children, ? marks an optional attribute, 1 means exactly one child expression, and — means the tag yields no value of its own. Slot tags — the children that carry a job title — are shown by name in the signature of the tag that owns them.

The attributes in the signature are the only ones a tag reads. Any other name — <join seperator="-"> for sep= — stops the run with TDC015 and the nearest real name, because a tag that ignored it would compute the value as if it were not written. comment= is accepted on every tag.

Literals and references

In depth: The compute sub-language

Tag	Signature	What it does
<int>	v= → int	An integer literal (attribute v)
<str>	v= → str	A string literal (attribute v)
<list>	v= or int… → list	A literal list of ints, or one built from nested expressions
<field>	name= → str	The value of a sequence in scope — the same as ${{X}}
<use>	name= → int|str|list	A value bound by <let>
<let>	name= + 1 → —	Name an intermediate result for sibling tags
<current>	→ int|str	The current iteration item (inside <do>)
<current_index>	→ int	The current item's index, counting from zero
<acc>	→ int|str|list	The accumulator (inside <reduce>)

Lists and iteration

In depth: Lists & iteration

Tag	Signature	What it does
<each>	<over> <do> → list	Transform every element → a new list
<reduce>	<over> <init> <do> → int|str|list	Fold a list into one value (<acc>)
<join>	list + sep=? → str	List → string (attribute sep)
<split>	str + sep= → list	String → list, cut on sep (required)
<at>	<in> <index> + default=? → int|str	An element by index (attribute default)
<length>	str|list → int	Length of a string or a list

Arithmetic

In depth: Arithmetic

Tag	Signature	What it does
<add>	int… → int	Sum of all children (empty → 0)
<subtract>	int… → int	First minus the sum of the rest
<multiply>	int… → int	Product (empty → 1)
<divide>	int int → int	Integer division toward −∞ (2 children)
<mod>	int int → int	Euclidean remainder, always ≥ 0

Strings, encoding, formatting

In depth: Strings & formatting

Tag	Signature	What it does
<encode>	str(1) + as= → str	Character → number (base36/ascii/hex/…)
<to_number>	str → int	Digit string → integer
<pad>	int|str + width= fill=? → str	Pad on the left to a given width (width, fill)
<concat>	int|str… → str	Join several parts into one string
<upper> / <lower>	str → str	Upper / lower case
<capitalize>	str → str	Uppercase the first letter
<title>	str → str	Uppercase the first letter of every word
<mask>	str + pattern= → str	Display mask (pattern: x/w/*)
<slice>	str + from= to=? → str	Substring [from, to)
<replace>	str + from= to= → str	Replace every occurrence (from, to)
<trim>	str → str	Strip surrounding whitespace
<group>	str + size=? sep=? → str	Group digits from the right (size, sep)

Conditionals

In depth: Conditionals

Tag	Signature	What it does
<choose>	<when>… <otherwise> → int|str|list	Choose a branch; requires an <otherwise>
<when>	<test> <then> → —	A branch: <test> predicate + <then> value
<otherwise>	1 → int|str|list	The "else" branch (required)
<test>	1 → yes|no	Holds one predicate, yields yes or no
<then>	1 → int|str|list	The value of the matched branch
<equals>	int int → yes|no	Predicate: two ints are equal
<greater_than>	int int → yes|no	Predicate: A > B
<less_than>	int int → yes|no	Predicate: A < B
<is_digit>	str(1) → yes|no	Predicate: a character is a digit 0–9

Wrappers and special

Tag	Signature	What it does
<over>	1 → str|list	The input list for <each> / <reduce>
<do>	1 → int|str|list	The iteration body for <each> / <reduce>
<init>	1 → int|str|list	The accumulator's starting value for <reduce>
<in>	1 → list	The list for <at>
<index>	1 → int	The item index for <at>
<result>	1 → int|str	The final value of a <compute>
<valid>	1 → —	Reject and retry until the value is valid

See the Compute Language section for worked examples.