featws-transpiler

0.7.4-rc1 verified Fri May 01 auth: no javascript

A transpiler that converts FeatWS files (features.json, parameters.json, rules.featws) into GRL (Grule Rule Language) format for use with the Grule rule engine (https://github.com/hyperjumptech/grule-rule-engine). Current version is 0.7.4-rc1 (release candidate) with frequent releases. Supports special markers (# for features, $ for parameters, @ for groups), group definitions, JSON rules, and extended feature format. Key differentiator: designed specifically for Banco do Brasil's FeatWS ecosystem, not a general-purpose transpiler.

Common errors

error Error: Cannot find module 'featws-transpiler' ↓

cause Package not installed or ESM import not configured correctly.

fix

Run 'npm install featws-transpiler'. For ESM, ensure package.json has 'type': 'module'.

error TypeError: features is not iterable ↓

cause features parameter passed as object instead of array.

fix

Ensure features.json is an array of objects, not a single object. Use JSON.parse(file) correctly.

error SyntaxError: Unexpected token '#' in rules.featws ↓

cause The # marker is not being recognized; may be due to incorrect context or missing feature definition.

fix

Declare the feature in features.json. Use extended format if needed. Ensure # is not escaped.

Warnings

breaking v0.7.0-rc1 changed parameters in transpile() call ↓

fix Refer to the changelog: resolve parameter renamed or reordered. Check the new signature in the source.

gotcha Default feature type is 'boolean' if not declared in features.json ↓

fix Always declare non-boolean features in features.json with explicit type.

gotcha Special markers #, $, @ are mandatory in rules.featws ↓

fix Use # for features, $ for parameters, @ for groups. Otherwise transpiler may fail silently.

deprecated v0.5.0-rc1 renamed 'resolve' parameter to something else ↓

fix Update your code to use the new parameter name (e.g., 'resolver' or similar). Check release notes.

Install

npm install featws-transpiler

yarn add featws-transpiler

pnpm add featws-transpiler

Imports

transpile
wrong
```
const transpile = require('featws-transpiler')
```
correct
```
import { transpile } from 'featws-transpiler'
```
ESM module. The package does not export a default function; use named import.

FeaturesFile

wrong

import FeaturesFile from 'featws-transpiler'

correct

import { FeaturesFile } from 'featws-transpiler'

Type is exported for TypeScript usage. Not a class for instantiation.

RulesFile

wrong

import { RuleFile } from 'featws-transpiler'

correct

import { RulesFile } from 'featws-transpiler'

Correct name is RulesFile (plural). Common misspelling as RuleFile.

Quickstart

Demonstrates reading required input files and calling the transpile function to generate GRL output.

import { transpile } from 'featws-transpiler';
import { readFileSync } from 'fs';

const features = JSON.parse(readFileSync('features.json', 'utf8'));
const parameters = JSON.parse(readFileSync('parameters.json', 'utf8'));
const rules = readFileSync('rules.featws', 'utf8');

const result = transpile(features, parameters, rules);
console.log(result.grlContent);