Morphs

Since environment variables are defined as strings, ArkEnv automatically transforms certain ArkType keywords when imported through ArkEnv instead of directly from ArkType. These "morphs" provide environment-variable-specific behavior that's optimized for configuration management.

Link to section: boolean#boolean

The boolean type automatically morphs (or coalesces) string values from environment variables to boolean.

import arkenv from 'arkenv';

const env = arkenv({ DEBUG: "boolean" });
const isDebug = env.DEBUG;

// Hover to see the type
console.log(isDebug);

Result:

❯ DEBUG=true npx tsx index.ts
true

This works by checking if the value is one of the following:

• "true"
• "false"

You can set boolean defaults:

const env = arkenv({ 
  DEBUG: "boolean = false",
  ENABLE_FEATURES: "boolean = true"
});

If you wish to customize this behavior (and allow other string representations of boolean), you can define your own morph function:

import arkenv, { type } from 'arkenv';

const env = arkenv({ 
  DEBUG: type("'true' | 'false' | '0' | '1'").pipe((str) => str === "true" || str === "1")
});
const isDebug = env.DEBUG;

console.log(isDebug);

Result:

❯ DEBUG=false npx tsx index.ts
false
❯ DEBUG=0 npx tsx index.ts
false
❯ DEBUG=true npx tsx index.ts
true
❯ DEBUG=1 npx tsx index.ts
true