# Steel Decimal

A Rust library that provides high-precision decimal arithmetic support for the [Steel programming language](https://github.com/mattwparas/steel). This crate transforms Steel scripts to use decimal operations and provides function registration utilities for Steel VMs.

## Features

- **High-precision decimal arithmetic** using `rust_decimal` crate
- **Automatic script transformation** from standard math to decimal operations  
- **Comprehensive mathematical functions** (basic arithmetic, trigonometry, logarithms)
- **Financial calculations** with proper decimal precision
- **Configurable precision control** 
- **Selective function registration** via builder pattern
- **Variable support** with validation
- **Thread-safe** precision contexts

## Quick Start

Add this to your `Cargo.toml`:

```toml
[dependencies]
steel_decimal = "1.0.0"
```

## Supported Operations

### Basic Arithmetic
- Addition: `(+ a b)` → `(decimal-add "a" "b")`
- Subtraction: `(- a b)` → `(decimal-sub "a" "b")`  
- Multiplication: `(* a b)` → `(decimal-mul "a" "b")`
- Division: `(/ a b)` → `(decimal-div "a" "b")`

### Advanced Mathematics
- Power: `(^ base exp)` → `(decimal-pow "base" "exp")`
- Square root: `(sqrt x)` → `(decimal-sqrt "x")`
- Natural log: `(ln x)` → `(decimal-ln "x")`
- Base 10 log: `(log10 x)` → `(decimal-log10 "x")`
- Exponential: `(exp x)` → `(decimal-exp "x")`

### Trigonometric Functions
- `(sin x)`, `(cos x)`, `(tan x)`

### Comparison Operations  
- `(> a b)`, `(< a b)`, `(= a b)`, `(>= a b)`, `(<= a b)`

### Financial Functions
- Percentage: `(decimal-percentage amount rate)`
- Compound interest: `(decimal-compound principal rate time)`

### Precision Control
- Set precision: `(set-precision 4)` 
- Get current precision: `(get-precision)`
- Clear precision: `(clear-precision)`

## Examples

The crate includes several examples:

```bash
# Basic usage
cargo run --example basic_usage

# Selective function registration  
cargo run --example selective_registration

# Working with variables
cargo run --example with_variables
```

## Scientific Notation Support

Steel Decimal supports scientific notation in decimal parsing:

```rust
let script = "(+ 1.5e2 2.3e-1)"; // 150 + 0.23 = 150.23
let transformed = steel_decimal.transform(script);
```

## Thread Safety

Precision settings are thread-local, allowing different threads to use different precision contexts safely.


## License

This project is licensed under either of

- Apache License, Version 2.0 ([LICENSE-APACHE](LICENSE-APACHE) or http://www.apache.org/licenses/LICENSE-2.0)
- MIT License ([LICENSE-MIT](LICENSE-MIT) or http://opensource.org/licenses/MIT)

at your option.