promptext

promptext is a small, type-safe DSL for building structured prompts in TypeScript.

It allows you to construct prompts from composable nodes (text, block, when, xml) instead of assembling strings manually.

Installation

npm install promptext

yarn add promptext

pnpm add promptext

Basic usage

import { text, block, when } from "promptext";

const prompt = block(
  text("Hello {name}!"),
  when("isAdmin", "You have admin access.", "You are a regular user.")
);

const output = prompt.render({
  name: "Nikolas",
  isAdmin: true,
});

Output

Hello Nikolas!

You have admin access.

TypeScript enforces required parameters:

prompt.render({
  name: "Nikolas",
});
// ❌ Property 'isAdmin' is missing

Why not just strings?

Before (plain strings)

let prompt = "";

prompt += `Hello ${name}!\n\n`;

if (isAdmin) {
  prompt += "Admin panel enabled.\n";
  prompt += `You have ${count} pending approvals.\n`;
} else {
  prompt += "Standard user mode.\n";
}

if (showFooter) {
  prompt += "\n---\n";
  prompt += footerText ?? "";
}

After (promptext)

const prompt = block(
  text("Hello {name}!"),

  when(
    "isAdmin",
    block(
      text("Admin panel enabled."),
      text("You have {count} pending approvals.")
    ).join("\n"),
    text("Standard user mode.")
  )
);

Text nodes

text("Hello {name}");

trim()

Useful for writing clean multi-line text:

text(`
Here everything starts inline
`).trim();

indent(level?)

Applies indentation at render time:

text("Indented").indent();
text("More indented").indent(2);

Blocks

block(text("Line one"), text("Line two"));

• Children are joined with two newlines (\n\n) by default
• join(separator) controls how children are joined
• indent(level?) indents the entire block

Conditional rendering

when("isAdmin", text("Admin mode"), text("User mode"));

• The key becomes a required boolean render parameter
• The else branch is optional

XML nodes

import { xml, text } from "promptext";

const prompt = xml(
  "user",
  xml("name", text("{name}")).indent(),
  xml("role", text("{role}")).indent()
);

prompt.render({
  name: "Nikolas",
  role: "admin",
});

Output

<user>
  <name>
  Nikolas
  </name>

  <role>
  admin
  </role>
</user>

License

MIT