§ 02 — Eras · 1995

PHP

code inside the page — the web’s long tail

Left: era context, features, and the 101 hello. Right: 3 core concepts, 3 deeper 201 lessons, the factorial specimen, and where PHP lives today — each column scrolls on its own.

see this language in the feature matrix

creators: Rasmus Lerdorf, 1995
status: alive · a large share of the web, WordPress, Laravel

The problem it solves

Dynamic pages required CGI gymnastics. PHP made the server-side behavior of a page as easy to write as the page itself.

The problem it carries

An stdlib that grew by accretion — inconsistent names, forgiving-by-default behavior, and a security reputation earned early.

Key features

templating in the page: HTML and code interleaved — the page is the program, and deploying is uploading a file.
superglobals and extensions: Request, session and filesystem are one function call away.
coercive typing: Types are checked and converted loosely, on purpose — the price of templating.
one array type: An ordered map does duty as list, dictionary and tuple alike.

101 — hello, world

Session one is the smallest program that still counts as speaking PHP: what every tutorial prints first, in the dialect that mattered when the language arrived (1995).

the first program1995

<?php
echo "Hello, world";

101First contact — hello world and 3 ideas that define how PHP reads. 201 — 3 lessons on mechanisms you meet after the factorial specimen: the sharp edges practitioners actually use.

101 — core concepts

3 fragments, each naming a habit of mind in PHP. Read the note, then the code — together they are the 101 in one sitting.

01 — tags in the page

The document is the program — deploy by uploading a file.

<h1>Crew</h1>
<?php foreach ($crew as $name): ?>
  <p><?= htmlspecialchars($name) ?></p>
<?php endforeach; ?>

02 — arrays (and hashtables)

One type — ordered map — does duty for list, dict and tuple.

$wage = ["perch" => 24, "sundial" => 31];
$wage["graymail"] = 12;
foreach ($wage as $k => $v) echo "$k: $v\n";

03 — functions & types (modern)

Modern PHP is typed, fast and boring in the best way.

function tally(array $xs): int {
  return array_sum($xs);
}

201 — going deeper

The 201 assumes you have read the 101 and the specimen. Each lesson is one mechanism — what it is for, how it looks in code, and the trap or payoff that makes PHP distinctive at scale.

modern typing
attributes and reflection
generators and iterators

modern typing

Union types, enums, readonly properties and never — PHP’s type system caught up with the decade, and static analysers can finally rely on it.

enum Port: string {
  case Osaka = "osaka";
  case Genoa = "genoa";
}

final class Ship {
  public function __construct(public readonly string $name) {}
}

attributes and reflection

Attributes put metadata in the source, readable by reflection — the basis for routing, validation and dependency injection without XML.

#[Route("/api/crew", methods: ["GET"])]
public function crew(): array { ... }

generators and iterators

A generator streams values without materialising an array — the answer to “this query returns a million rows”.

function crew(): Generator {
  foreach ($this->rows as $row) {
    yield $row['name'] => $row['tons'];
  }
}

The specimen — factorial

The page template: code inside the document, the document inside the code — the long tail of the web, written between two tags.

the page template1995

<ul>
<?php foreach ($crew as $name): ?>
  <li><?= htmlspecialchars($name) ?></li>
<?php endforeach; ?>
</ul>

Run it today

installbrew install php

runphp fact.php

Where it is now

WordPress alone runs ~40% of the web; Laravel is one of the most pleasant frameworks anywhere.