Materialize typescript functions

A simple cli command to materialize the response of a typescript async function during build time.

The simplest use-case

1. Annotate your function with @materialized

import { readFile } from "fs/promises";

/**
 * @materialized
 */
async function getVersion() {
	// return anything that survives JSON.stringify()

	const pkg = await readFile("./package.json");
	const parsed = JSON.parse(pkg.toString());
	return parsed.version;
}

2. Rewrite the code during build

npx materialize-ts-function

3. End result

/**
 * @materialized
 */
async function getVersion() {
	/* __materialized__ */
	return "1.0.0";
}

Conditionally skipping materialize

Use any boolean returning expression with @if annotation

/**
 * @materialized
 * @if process.env.DEBUG !== undefined
 */
async function someComplexLogic() {
	// add business logic here
}

How it works internally

We scan the codebase for all files containing functions with the @materialized annotation and temporarily add a simple statement to the end of the file to make it executable with ts-node.

Then we capture the output and replace the annotated functions body with the serialized response from the ts-node execution.

// Temporary statements to execute the function
import { materialize } from "materialize-ts-function";

materialize(
	someComplexLogic, // <-- @materialized function
	process.env.DEBUG !== undefined // <-- @if annotation literal
)
	.then(console.log)
	.catch(console.error);

To debug one can add the same statement to the file and execute if with

ts-node ./src/original/file/location.ts

Thats it ...

... happy coding :)