Templates

Template literals work as in JavaScript: text in backticks with ${expression} interpolations.

`Hello ${user.name}!` // => "Hello Ada!"
`Order ${order.id}: ${cart.items.length} items, ${order.total} total` // => "Order A-1042: 3 items, 129.5 total"
`${user.nickname ?? user.name} (${user.tags.join(", ")})` // => "Ada (admin, beta)"

Templates can span lines and nest, and \${ writes a literal ${:

`Dear ${user.name},
your order ${order.id} has shipped.` // => "Dear Ada,\nyour order A-1042 has shipped."
`a ${`b ${1 + 1}`} c` // => "a b 2 c"
`\${not interpolated}` // => "${not interpolated}"

How values render

Value	Rendered as
null	empty text
string	the string
boolean	true or false
number	shortest round-trip form, as JavaScript's String(n)
timestamp	ISO-8601, for example 2026-01-14T09:00:00.000Z
duration	ISO-8601 duration, for example PT1H30M
list or map	a type error

`[${user.nickname}]` // => "[]"
`${0.1 + 0.2}` // => "0.30000000000000004"
`${order.placedAt}` // => "2026-01-14T09:00:00.000Z"
`${hours(1.5)}` // => "PT1H30M"
`${user.tags}` // error: TYPE_ERROR

Lists and maps have no single obvious text form, so render them explicitly with join, a nested template, or a function such as formatDate or toFixed:

`Tags: ${user.tags.join(", ")}` // => "Tags: admin, beta"
`Placed ${order.placedAt.formatDate("dd/MM/yyyy")}` // => "Placed 14/01/2026"
`Total: ${order.total.toFixed(2)}` // => "Total: 129.50"

toString(x) renders a value the same way a template does.

Templates never call toString, valueOf, or toJSON on host objects, and the produced text counts against the maxStringLength limit.