Lykn

Tagged Templates

The tag form applies a function to a template:

(tag html (template "<p>" user-input "</p>"))

html`<p>${userInput}</p>`

What Tag Functions Receive

A tag function receives the literal parts and interpolated values separately. The literal parts arrive as an array of strings; the values arrive as additional arguments. This separation is what makes tagged templates powerful — the function can process values before assembling the result.

Use Cases

Tagged templates power some of JavaScript’s most widely used libraries:

• HTML escaping: html tag functions sanitize interpolated values, preventing XSS
• CSS-in-JS: styled-components and lit-html use tagged templates for component styles
• SQL queries: tag functions parameterize interpolated values, preventing SQL injection
• Internationalization: tag functions look up translations for the literal parts

String:raw

JavaScript’s built-in String.raw tag returns the raw string without processing escape sequences:

(bind path (tag String:raw (template "C:\new\test")))

String.raw`C:\new\test`

The backslashes are literal — \n is not a newline, it’s a backslash followed by n. Useful for regular expressions, file paths, and any context where you want literal backslashes.

A Note on Usage

Most Lykn developers will use tagged templates (calling library-provided tag functions) rather than write them (implementing tag functions). The pattern is worth knowing — when you encounter html or css or sql tags in a library, you’ll understand what they do and why they’re safe.