TaggedTemplate

Utilities for working with JavaScript tagged templates.

A value of type TaggedTemplate.t<'param, 'output> can be used directly with backtick syntax, and the compiler emits a real JavaScript tagged template literal at every call site — across module boundaries, when stored in a value, or when passed as a function argument:

RES
@module("./sql_client.js")
external sql: TaggedTemplate.t<'a, promise<queryResult>> = "sql"

let users = await sql`SELECT * FROM users WHERE id = ${userId}`

make(tag) lifts a plain ReScript function of the tag-function shape (array<string>, array<'param>) => 'output into a t<'param, 'output>, so it can itself be used with tagged-template backtick syntax — emitting real JavaScript tagged-template syntax at every call site.

Examples

RES
type params = I(int) | S(string)

let s = TaggedTemplate.make((strings, parameters) => {
  Array.reduceWithIndex(parameters, Array.getUnsafe(strings, 0), (acc, param, i) => {
    let suffix = Array.getUnsafe(strings, i + 1)
    let p = switch param {
    | I(i) => Int.toString(i)
    | S(s) => s
    }
    acc ++ p ++ suffix
  })
})

let greeting = s`hello ${S("Ada")} you're ${I(36)} years old!`

Type of a tagged template tag. 'param is the type accepted in ${...} interpolations, 'output is the type produced by the tag.