product-farm-farmscript

Human-friendly DSL that compiles to JSON Logic for intuitive rule authoring.

Overview

FarmScript is a domain-specific language designed for business users to write rules without learning JSON Logic syntax. It compiles to JSON Logic for execution.

Write this:

if age < 25 then base_rate * 1.5
else if age < 35 then base_rate * 1.2
else base_rate

Instead of this:

{
  "if": [
    {"<": [{"var": "age"}, 25]}, {"*": [{"var": "base_rate"}, 1.5]},
    {"<": [{"var": "age"}, 35]}, {"*": [{"var": "base_rate"}, 1.2]},
    {"var": "base_rate"}
  ]
}

Features

• Natural syntax - Reads like English, not code
• Type inference - Automatic type detection from context
• Error messages - Clear, actionable error descriptions
• Zero runtime - Compiles to JSON Logic at build time
• IDE support - Syntax highlighting and completion (coming soon)

Part of Product-FARM

This crate is part of Product-FARM, an enterprise-grade rule engine featuring:

• 3M+ evaluations/sec with bytecode compilation
• Natural language YAML - Define products in human-readable format
• LLM-powered evaluation - Use AI for complex rule interpretation
• 1 million rules tested at 96k rules/sec

Installation

[dependencies]
product-farm-farmscript = "0.2"

Usage

use product_farm_farmscript::{Parser, compile_to_json_logic};

// Parse and compile FarmScript
let script = r#"
    if customer_type == "premium" then
        base_price * 0.9
    else if quantity > 100 then
        base_price * 0.95
    else
        base_price
"#;

let json_logic = compile_to_json_logic(script)?;
// Now execute with product-farm-json-logic or product-farm-rule-engine

Syntax Reference

Variables

age                    # Simple variable
customer.address.city  # Nested access
items[0].price         # Array access

Operators

# Arithmetic
price + tax
total - discount
quantity * unit_price
amount / count

# Comparison
age < 25
status == "active"
score >= threshold

# Logical
is_member and has_discount
is_premium or is_vip
not is_blocked

Conditionals

if condition then result

if condition then
    result_a
else
    result_b

if condition_1 then result_1
else if condition_2 then result_2
else default_result

Functions

min(a, b, c)
max(price, floor_price)
round(calculated_value, 2)

Related Crates

Documentation

• Product-FARM Documentation
• API Reference
• FarmScript Guide

License

MIT License - see LICENSE for details.