tetthys/wrap

Minimal Result-like wrapper with fluent map/filter/reduce and conditional helpers for PHP 8.3+.

0.1.2 2025-12-13 17:42 UTC

Requires

• php: ^8.4

Requires (Dev)

• pestphp/pest: ^2.34

MIT

README

A minimal, fluent Result-like wrapper for PHP 8.3+.

• Safely execute code and keep either a value (ok) or a captured exception (fail)
• Transform values (then, map, filter, reduce)
• Use expressive flow helpers (when, unless, branch)
• Add modern chain helpers (andThen, ensure, recoverWhen, mapError, rethrowWhen, tap, tryTap, failWhen)
• Support optional pipelines (keep, whenValue, whenValueThen) and error side-effects (tapError, tryTapError)
• Make exception behavior explicit with safe*, try*, and rethrow* helpers

Installation

composer require tetthys/wrap

Quick Start

use Tetthys\Wrap\Wrap;

$result = Wrap::handle(fn() => riskyOperation())
    ->tryOk(fn($v) => logger()->info('ok', ['value' => $v]))       // swallows callback exceptions
    ->tryFail(fn($e) => logger()->warning('fail', ['msg' => $e->getMessage()])) // swallows callback exceptions
    ->rescue(fn() => 42)                                          // recover from failure
    ->then(fn($v) => $v * 2)
    ->getValueOr(0);

echo $result; // 84

Exception Policy (Important)

Wrap deliberately separates how exceptions are handled by method name. You should be able to tell whether an exception is thrown, captured, or swallowed just by reading the chain.

1) Thrown (escape the Wrap boundary)

These methods do not catch exceptions from callbacks or explicitly rethrow errors:

• then, map, filter, reduce
• ok, fail
• rethrowWhen
• rescueWhen (when predicate does not match)
• rescueExcept (when error matches except list)
• throwIfFailed, rethrow, rethrowRoot

Use these when an error must propagate to the caller.

2) Captured (invalidate the chain)

These methods catch exceptions and convert them into a failed Wrap state (using InvalidArgumentException with the original error as previous):

• safeThen, safeMap, safeFilter, safeReduce
• tap, tapError
• when, unless, branch
• ensure, safeKeep
• whenValue, whenValueThen
• Added: safeOk, safeFail

Use these when errors should stay inside the Wrap pipeline.

3) Swallowed (ignored)

These methods ignore callback exceptions entirely and keep the current state:

• tryTap, tryTapError
• Added: tryOk, tryFail

Use these for logging, metrics, tracing, or any side effects that must never break the flow.

Recommended rule of thumb

• Logging / metrics / monitoring → try*
• Business logic that may fail → safe*
• Domain or application boundaries → throwIfFailed / rethrow*

Construction

Wrap::handle(callable $callback)

Runs a callback and captures its return value or any thrown Throwable.

$wrap = Wrap::handle(fn() => 42);
$wrap = Wrap::handle(fn() => throw new RuntimeException('boom'));

Wrap::fromValue(mixed $value)

Creates a successful Wrap.

$wrap = Wrap::fromValue(['a' => 1]);

Wrap::fromError(Throwable $error)

Creates a failed Wrap.

$wrap = Wrap::fromError(new RuntimeException('x'));

Side Effects

ok(callable $callback) / fail(callable $callback)

Runs only on success / failure.

⚠ If the callback throws, the exception is thrown immediately.

Wrap::handle(fn() => 10)
    ->ok(fn($v) => logger()->info("Value: $v"));

safeOk(callable $callback) / safeFail(callable $callback) ✅

Runs only on success / failure.

If the callback throws, the chain is invalidated.

Wrap::handle(fn() => 10)
    ->safeOk(fn($v) => riskyLog($v))
    ->then(fn($v) => $v + 1);

tryOk(callable $callback) / tryFail(callable $callback) ✅

Runs only on success / failure.

If the callback throws, the exception is swallowed.

Wrap::handle(fn() => 10)
    ->tryOk(fn($v) => riskyLog($v))
    ->then(fn($v) => $v + 1);

always(callable $callback): void

Always runs (finally-style) and ends the chain.

Receives (bool $ok, ?Throwable $error, mixed $value).

finally(callable $callback)

Always runs and continues the chain. If the callback throws, the chain is invalidated.

Transformations

then(callable $callback)

Transforms the stored value on success.

⚠ If the callback throws, the exception is thrown.

$out = Wrap::handle(fn() => 10)
    ->then(fn(int $x) => $x + 5)
    ->then(fn(int $x) => (string) ($x * 2))
    ->getValueOr('fallback');

safeThen(callable $callback)

Catches exceptions and invalidates instead of throwing.

Iterable Operators

map, filter, and reduce require the stored value to be iterable.

• map / filter / reduce → throw
• safeMap / safeFilter / safeReduce → invalidate

Recovery

rescue(callable $fallback)

On failure, provides a fallback value and flips the state to success.

✅ The fallback may accept zero arguments or one Throwable argument.

Wrap::handle(fn() => throw new RuntimeException('oops'))
    ->rescue(fn() => 123)
    ->getValueOr(-1);

Wrap::handle(fn() => throw new RuntimeException('oops'))
    ->rescue(fn(Throwable $e) => 123);

recoverWhen(string|callable $matcher, callable $fallback)

Recover only when the failure matches a class-string or predicate.

Flat-mapping

andThen(callable $callbackReturningWrap)

Like then(), but flattens another Wrap into the chain.

Validation

ensure(callable $predicate, string|callable $message = 'Ensure failed')

Invalidates the chain when the predicate returns false.

Optional Value Flow

Helpers for pipelines where null means “no work to do”:

• keep, safeKeep
• whenValue, whenValueThen

Error Utilities

throwIfFailed(?callable $factory = null) ✅

Escapes the Wrap boundary. Throws the captured error if failed.

rethrow() ✅

Throws the captured error as-is. If invalidated, throws the wrapper exception.

rethrowRoot() ✅

Throws the root cause error (the previous exception when wrapped).

Wrap::handle(fn() => 1)
    ->safeThen(fn() => throw new RuntimeException('root'))
    ->rethrowRoot();

rethrowWhen(string|callable $matcher)

Throws the captured error only when it matches.

tapError / tryTapError

• tapError → callback throws → invalidate
• tryTapError → callback throws → swallow

Extraction & Accessors

• isOk()
• getError()
• getValue()
• getValueOr()
• getValueOrCall()
• getValueOrNull()
• getOrThrow()

Optional Global Helper

function wrap(callable $callback): Wrap
{
    return Wrap::handle($callback);
}

License

MIT