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tacoberu/hayo
=============

Lightweight purely functional scripting runtime with static typing and type inference.

v0.3.8(1mo ago)115↓88.9%[2 issues](https://github.com/tacoberu/php-hayo/issues)MITPHPPHP >=7.4CI passing

Since Jun 2Pushed 1mo agoCompare

[ Source](https://github.com/tacoberu/php-hayo)[ Packagist](https://packagist.org/packages/tacoberu/hayo)[ RSS](/packages/tacoberu-hayo/feed)WikiDiscussions v0.3 Synced 1w ago

READMEChangelogDependencies (14)Versions (7)Used By (0)

php-hayo
========

[](#php-hayo)

[![License](https://camo.githubusercontent.com/7013272bd27ece47364536a221edb554cd69683b68a46fc0ee96881174c4214c/68747470733a2f2f696d672e736869656c64732e696f2f62616467652f6c6963656e73652d4d49542d626c75652e737667)](LICENSE)[![PHP Version](https://camo.githubusercontent.com/9f214dca45a1f32017a93d36952527052a2530721f1dc1f2abc678efe431d048/68747470733a2f2f696d672e736869656c64732e696f2f62616467652f7068702d253345253344253230372e342d3838393262662e737667)](https://php.net)[![Tests Status](https://github.com/tacoberu/php-hayo/actions/workflows/tests.yml/badge.svg)](https://github.com/tacoberu/php-hayo/actions/workflows/tests.yml/badge.svg)

Hayo is a lightweight, purely functional scripting language / runtime implemented in PHP. It is designed for interpreting user-defined logic (conditions, transformations, business rules) from scripts that you may want to store (for example) in a database and keep user-editable. You pass a script as a string, compile it into a function, and then call that function with concrete data.

Read the **[language syntax reference](docs/syntax.md)** and the **[built-in function reference](docs/libs.md)**.

---

💡 Why Hayo?
-----------

[](#-why-hayo)

- **🛡️ Security by Isolation:** Purely functional, no side-effects. Scripts have zero access to the filesystem, network, or global PHP state. It is a safe way to run user-provided logic.
- **💾 Persistence & Caching:** Compiled, optimized bytecode can be transparently cached. The result is already a fast function.
- **🧠 Expressiveness:** The language supports local variables, lambdas, and pattern matching.
- **🔍 Static Analysis:** Includes type inference and compile-time validation to catch most embarrassing errors.

---

🚀 Quick Start
-------------

[](#-quick-start)

```
composer require tacoberu/hayo
```

```
use Taco\Hayo\HayoEngine;

$engine = HayoEngine::WithDefaultLibraries();

// Simple evaluation
$engine->evaluate("1 + 1"); // 2

// With arguments
$engine->evaluate("a + b", ["a" => 1, "b" => 2]); // 3
```

---

💡 Real-world Example: Business Logic
------------------------------------

[](#-real-world-example-business-logic)

Hayo elegantly handles complex branching and data transformations:

```
-- Calculate total from an array of dictionaries
totalPrice = order.items
    |> List.map (i -> i.price * i.quantity)
    |> List.fold 0 (acc curr -> acc + curr)

-- Condition with branching and pattern matching
if totalPrice > 1000 or order.customer.isVip then
    totalPrice * 0.9 -- 10% discount
else
    totalPrice

```

---

⚖ Comparison with Alternatives
------------------------------

[](#-comparison-with-alternatives)

The most common alternative for PHP is [Symfony Expression Language](https://packagist.org/packages/symfony/expression-language). Below is how they compare:

FeatureHayoSymfony Expression LanguageCustom functions✅✅Local variables in script✅⚠️ injection onlyLambdas / Closures✅❌Map / fold / filter✅⚠️ via extensionsBranching (if-else)✅⚠️ ternary onlyPattern Matching (match)✅❌Type Inference✅❌---

🏗 Usage & Integration
-------------------------

[](#-usage--integration)

### Bytecode caching

[](#bytecode-caching)

For repeated execution, use a cache adapter to avoid re-compiling the script:

```
$engine->setCache(new MyCacheAdapter())
    ->evaluate("1 + a", ["a" => 1]);
```

### Custom function libraries

[](#custom-function-libraries)

You can extend Hayo with your own PHP-defined functions.

```
$engine->registerLibrary(new MyStringsProvider())
    ->evaluate('MyStrings.format("result: ${0}", [1 + a])', ["a" => 1]);
```

### Local functions and lambdas

[](#local-functions-and-lambdas)

You can define functions within your script:

```
HayoEngine::WithDefaultLibraries()
    ->evaluate("
inc = x -> x + 1
inc counter
    ", ["counter" => 41]); // 42
```

### Higher-order functions — map, fold, and more

[](#higher-order-functions--map-fold-and-more)

```
HayoEngine::WithDefaultLibraries()
    ->evaluate("List.map xs (x -> x * x)", ["xs" => [1, 2, 3]]); // [1, 4, 9]
```

### Pipe chains operator

[](#pipe-chains-operator)

```
HayoEngine::WithDefaultLibraries()
    ->evaluate("
xs
    |> List.map (x -> x * x)
    |> List.fold 0 (prev curr -> prev + curr)
    ", ["xs" => [1, 2, 3, 4]]); // 30
```

---

⚠️ Exceptions
-------------

[](#️-exceptions)

The engine distinguishes between three phases where an error can occur:

### Compilation Errors

[](#compilation-errors)

Occur during `evaluate()` or `compile()`.

- `CompileException`: Syntax error in the script — invalid source code, unrecognized token, incomplete expression, or unresolved expression.
- `SymbolNotFound`: Script refers to a symbol, built-in, or library function that is not available in the runtime (not registered or a typo in the name).

### Argument Errors

[](#argument-errors)

Occur when calling a compiled script with concrete data.

- `ArgumentsException`: Script was called with wrong parameters — wrong name, count, or value type.

### Runtime Errors

[](#runtime-errors)

Occur during script execution.

- `ScriptRuntimeException`: Any error during execution — wrong argument type for a built-in function, division by zero (div, mod), etc. Wraps all Throwables that occurred during evaluation. The original cause is available via getPrevious().

---

📐 Built-in Functions
--------------------

[](#-built-in-functions)

Read the **[complete built-in function reference](docs/libs.md)**.

- **Math:** `+`, `-`, `*`, `div`, `mod`, `Math.ceil`, `Math.floor`, `Math.round`.
- **Strings (Str):** `len`, `split`, `concat`, `format`, `indexOf`, `contains`, `startsWith`, `endsWith`, `sub`, `toUpper`, `toLower`, `trim`.
- **Lists (List):** `len`, `first`, `at`, `exist`, `concat`, `push`, `indexOf`, `slice`, `split`, `map`, `fold`, `filter`, `sort`.
- **Dictionaries (Dict):** `has`, `get`, `merge`, `keys`, `values`.
- **DateTime:** `fromDate`, `fromDateTime`, `fromTimestamp`, `toTimestamp`, `format`.
- **Introspect:** `of`, `is`.

---

Architecture
------------

[](#architecture)

- `hayo-ast`: AST node definitions.
- `hayo-parser`: Default recursive descent parser.
- `hayo`: Runtime and compiler for PHP.

###  Health Score

29

—

LowBetter than 57% of packages

Maintenance70

Regular maintenance activity

Popularity8

Limited adoption so far

Community6

Small or concentrated contributor base

Maturity28

Early-stage or recently created project

 Bus Factor1

Top contributor holds 100% of commits — single point of failure

How is this calculated?**Maintenance (25%)** — Last commit recency, latest release date, and issue-to-star ratio. Uses a 2-year decay window.

**Popularity (30%)** — Total and monthly downloads, GitHub stars, and forks. Logarithmic scaling prevents top-heavy scores.

**Community (15%)** — Contributors, dependents, forks, watchers, and maintainers. Measures real ecosystem engagement.

**Maturity (30%)** — Project age, version count, PHP version support, and release stability.

###  Release Activity

Cadence

Every ~0 days

Total

6

Last Release

48d ago

### Community

Maintainers

![](https://avatars.githubusercontent.com/u/1828339?v=4)[Martin Takáč](/maintainers/tacoberu)[@tacoberu](https://github.com/tacoberu)

---

Top Contributors

[![tacoberu](https://avatars.githubusercontent.com/u/1828339?v=4)](https://github.com/tacoberu "tacoberu (81 commits)")

---

Tags

languageruntimefunctionalscriptingexpression-languageinterpreterstatic typingtype-inference

###  Code Quality

TestsPHPUnit

Static AnalysisPHPStan, Rector

Type Coverage Yes

### Embed Badge

![Health badge](/badges/tacoberu-hayo/health.svg)

```
[![Health](https://phpackages.com/badges/tacoberu-hayo/health.svg)](https://phpackages.com/packages/tacoberu-hayo)
```

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