Data model

The value system that data-defs, records, collections, captures, and load all share: six value kinds, their JSON mapping, access paths, conditions, and text coercion. Source: packages/parser/src/ast.ts.

The six DataValue kinds

DataValue kinds
Kind	Literal form	Standalone render
stringValue	prose or a quoted string	escaped text
numberValue	42 or 3.14	the number as text
booleanValue	true or false	true or false as text
nullValue		empty in a table cell
record	a brace map	a wit-record table
collection	a bracket list	a wit-collection list

#title: Field notes          ~ stringValue
#count: 42                    ~ numberValue
#draft: true                  ~ booleanValue
#note: null                   ~ nullValue
#site: { name - Docs, year - 2026 }   ~ record
#tags: [ ref, spec, wit ]     ~ collection

Records carry an ordered fields list of key/value pairs; collections carry an ordered items list. Data-def records need the hyphen delimiter; the colon form is call-site only.

Access paths

A dotted lookup selects a field. Access is fuzzy: camelCase, snake_case, and spaced keys all match.

#person: { firstName - Ada, role - Author }

Name is @person.first_name → Name is Ada

Iteration

(each @collection as item) … (end) binds each element to item. Inside the loop, reference it with @item (a bare reference), or @item.field for a record field — not ::item:: (that is capture interpolation, a different mechanism).

source

#hands: [ { name - Marlow }, { name - Singleton } ]

@ul
(each @hands as item) @li @item.name li@ (end)
ul@

result

Marlow

Singleton

Iterating a non-collection raises E_NOT_ITERABLE. Fixture: 13-iteration/*.

Conditions

The test in an (if …) is either existence or a comparison.

Condition forms
Form	True when
if path	the path resolves to a value
if path is X	the value equals X — identity
if path equals X	the value equals X — comparison

(if @author) By @author.name (end)
(if @status is shipped) Live (else) Draft (end)

Fixture:

12-conditionals/*.

JSON to Wit mapping

The only shape that crosses the load seam.

JSON to Wit
JSON	Wit value
object	record
array	collection
string	stringValue
number	numberValue
boolean	booleanValue
null or undefined	nullValue

Text coercion

When a value is placed in text (a table cell or inline), it is coerced: number and boolean → their string form; nullValue → an empty string.

typedValue

A capture param carries a shape-probed typedValue when it looks like a collection, record, or scalar literal; pure prose keeps only its string value. This is what lets |rows @ref| and typed captures work — the table renderer reads typedValue.