Introduction

StirPHP is to PHP what TypeScript is to JavaScript: a strictly typed superset that compiles to the language you already deploy. You write .sphp files, the checker proves them consistent, and the compiler emits ordinary PHP 8.4, with PHPDoc that PHPStan understands.

const GREETING = "Hello"

function greet(name: String, mut times: Int = 1): String {
    var $out = ""
    while (times > 0) {
        $out .= "${GREETING}, ${name}! "
        times -= 1
    }
    return $out
}

val message = greet("world", 2)
echo message

What StirPHP adds

• A type system that means it. StirPHP's own types (Int, String, List<T>, ...) never coerce, null is a separate type, and there is no top type to escape into. See Types and null safety.
• Mutability you can see. val name never changes; var $name does, and keeps its $ everywhere it is used. See Values and variables.
• Better building blocks. Records (typed arrays), data classes, sealed hierarchies with exhaustive when, generics with variance, lambdas and extension functions.
• Tooling. sphp check, sphp build, sphp build --watch, and a language server for your editor.

What it keeps

StirPHP is PHP underneath. -> accesses members, . concatenates, namespaces, use, new, try/catch and PHP's functions all work as usual. Plain .php files can live next to .sphp ones, and their PHPDoc is read the way PHPStan reads it, so a project can move over one file at a time. See Working with PHP.

Status

StirPHP is young. The language, checker, compiler and language server work end to end (Parsedown has been ported to it, with its test suite passing), but the language may still change before 1.0.

Next: Installation.