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Compile-Time Constants

Module-level const declarations are evaluated at compile time and inlined into the ASL output. No runtime lookup is needed.

Basic Constants

const API_VERSION = 'v2';
const MAX_RETRIES = 3;
const TIMEOUT_MS = 30 * 1000;  // folds to 30000

When referenced inside a Steps.createFunction(), these values are inlined directly into ASL Parameters as literals.

Constant Folding

The compiler evaluates expressions involving only constants at compile time.

Arithmetic

const TIMEOUT_MS = 30 * 1000;           // -> 30000
const HALF = 100 / 2;                   // -> 50
const OFFSET = 10 + 5 - 3;             // -> 12

Supported operators: +, -, *, /, %.

String Concatenation

const BASE_PATH = '/api/' + API_VERSION;  // -> "/api/v2"

Template Literals

const GREETING = `Welcome to API ${API_VERSION}`;  // -> "Welcome to API v2"

Math.* Functions

The following Math methods are evaluated at compile time when all arguments are constants:

Function Example
Math.floor(x) Math.floor(3.7) -> 3
Math.ceil(x) Math.ceil(3.2) -> 4
Math.round(x) Math.round(3.5) -> 4
Math.abs(x) Math.abs(-5) -> 5
Math.sqrt(x) Math.sqrt(16) -> 4
Math.trunc(x) Math.trunc(3.7) -> 3
Math.sign(x) Math.sign(-5) -> -1
Math.log(x) Math.log(1) -> 0
Math.log2(x) Math.log2(8) -> 3
Math.log10(x) Math.log10(1000) -> 3
Math.min(a, b, ...) Math.min(3, 1, 2) -> 1
Math.max(a, b, ...) Math.max(3, 1, 2) -> 3
Math.pow(x, y) Math.pow(2, 10) -> 1024

Object and Array Literals

Constants can be objects or arrays if all values are themselves constants:

const DEFAULT_CONFIG = { retries: 3, timeout: 5000 };
const VALID_STATUSES = ['pending', 'active', 'complete'];

Example

const API_VERSION = 'v2';
const BASE_PATH = '/api/' + API_VERSION;
const MAX_RETRIES = 3;
const TIMEOUT_MS = 30 * 1000;
const GREETING = `Welcome to API ${API_VERSION}`;

export const workflow = Steps.createFunction(
  async (context: SimpleStepContext, input: { userId: string }) => {
    const result = await userService.call({
      path: BASE_PATH,        // inlined as "/api/v2"
      retries: MAX_RETRIES,   // inlined as 3
      timeout: TIMEOUT_MS,    // inlined as 30000
    });
    return { data: result.data, greeting: GREETING };
  },
);

What Is NOT Folded

  • let and var declarations -- only const is folded
  • Runtime values -- function parameters, service call results, context.*
  • String methods -- 'hello'.toUpperCase() is not folded
  • User-defined functions -- myFunction(42) is not folded
  • Non-Math pure functions -- only Math.floor/ceil/round/abs/sqrt/trunc/sign/log/log2/log10/min/max/pow are supported
  • Constants declared inside Steps.createFunction() -- only module-level constants are folded

See examples/showcase/21-constants.ts for a working example.