HTML

All Standard Input Types

HTML5 input types each have built-in validation, on-screen keyboards (mobile), and pickers. Use them — `<input type="number">` beats `<input type="text">` + JS validation every time.

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HTML

Card Pattern (article + link wrapper)

The standard content card — image, title, excerpt, meta. Make the WHOLE card clickable by wrapping the title link and using `::after` to extend the hit area to the full card.

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Kotlin

Generic Class and Function

`<T>` declares a type parameter. Use it on classes (`Box<T>`) and functions (`fun <T> identity(x: T) = x`). Type bounds (`T : Comparable<T>`) constrain what T can be.

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Bash

Find Largest Files and Directories

Quick "where did all my disk go?" answer. du sorts by size, ncdu (interactive) is better for exploration.

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Rust

Box<dyn Error> — Quick Boxed Errors

If you don't want the thiserror/anyhow dependency, `Box<dyn std::error::Error>` works as a catch-all. The `?` operator promotes any concrete error via `From`.

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HTML

Comment / Review Markup with Schema

Comments and reviews can also have Schema.org markup. The `Review` type appears under products in Google search results with star ratings; `Comment` is for general user feedback.

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Rust

Group By a Key (fold into HashMap)

No built-in `group_by`, but `fold` into a `HashMap` does the same thing in two lines — and the type system tracks keys / values correctly.

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Python

JWT Sign + Verify (PyJWT)

The de-facto JWT library for Python. HS256 demo with an exp claim and the standard "verify everything" decode flow. Mind that PyJWT raises specific exceptions you can catch separately.

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Rust

Custom Error Type with thiserror

The `thiserror` crate generates a clean `Error + Display + Debug` impl from an enum, with automatic `From` conversions. The library-author's error-type tool of choice.

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Java

try-with-resources

For any `AutoCloseable` (files, streams, DB connections, locks), declare it in `try(...)` and Java auto-calls `close()` even on exception. Replaces error-prone `try / finally` blocks.

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Java

CountDownLatch — Wait for N Events

Block one or more threads until a count of events occurs. Set the count up front; each event calls `countDown()`; waiters call `await()`. Classic "wait until all workers are ready" pattern.

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Kotlin

Smart Casts

After a successful `is` check (or null check), the compiler "smart-casts" the variable to the narrower type in that scope. No explicit cast needed.

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Rust

flat_map and Iterator::flatten

`flat_map(f)` is `map(f).flatten()` — map each item to an iterator, then concatenate. Indispensable for working with nested structures.

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Java

flatMap — Flatten Nested Streams

Map each element to a Stream, then concatenate all of them into one. Used everywhere from "all words from a list of sentences" to "all permissions from a list of roles".

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Java

Virtual Threads (Java 21+)

Java 21's virtual threads are millions-of-them cheap — JVM multiplexes them onto a small carrier pool. Replaces async/reactive code for most I/O-bound workloads: just write blocking code that doesn't actually block a kernel thread.

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Python

take / drop / takewhile

Take the first N items of an iterable (or while a predicate holds). drop is the complement. Lazy via islice + itertools.dropwhile — works on infinite generators.

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Java

Optional Chains — flatMap, filter

`flatMap` lets you chain Optional-returning methods without nested `if`. `filter` short-circuits to empty if the predicate fails. The functional equivalent of safe-navigation `?.`.

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PHP

URL-Safe Base64 Encode / Decode

Standard base64 uses + and / which break in URLs. Swap them for - and _, drop the = padding, and you get a string you can put in path segments and query parameters safely.

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PHP

Validate Email (RFC-aware)

Use PHP's built-in FILTER_VALIDATE_EMAIL with the FILTER_FLAG_EMAIL_UNICODE flag for IDN domains, plus a length sanity check. Trust this over hand-rolled regex.

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Bash

Kill Process by Port

When a port is "already in use" — find the offending process and (carefully) kill it. `lsof` is the gold standard; `ss` is the lighter modern alternative.

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PHP

PDO Schema Existence Checks

Idempotent helpers to test whether a table, column, or index already exists — handy when writing your own migration runner without an ORM.

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Java

java.time — Duration and Period

`Duration` for elapsed time (hours/minutes/seconds). `Period` for calendar amounts (days/months/years). Don't mix — calendar math respects month lengths and DST; clock math doesn't.

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Rust

axum — Hello World HTTP Server

axum is the tokio-team's web framework — composable, type-safe handlers built on tower middleware. The hello-world is small enough to read in one screen.

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Go

time.Since — Easy Benchmark Timing

`time.Since(start)` is shorthand for `time.Now().Sub(start)`. Pair with `defer` for a quick "how long did this function take?" measurement.

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Go

Generic Map / Filter / Reduce

Three classic functional combinators, generically typed. Go's standard library doesn't ship these (yet), but they're short enough to drop into any project.

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Java

Optional with Streams

`Optional::stream` (Java 9+) bridges optionals into the Stream API — collect all the `Some` values from a list of optionals, drop the empties, in one pipeline.

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Bash

Print Environment Variables Matching Pattern

Quick audit of env vars by prefix — useful when debugging containerized apps that read from `STRIPE_*`, `DB_*`, etc.

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Rust

Threads with thread::spawn + join

Native OS threads with `std::thread::spawn`. The returned `JoinHandle` lets you wait for the thread and get its return value. Use `move` to transfer ownership of captured variables.

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Rust

reqwest POST JSON

Send a JSON body by calling `.json(&value)` — serde handles serialization. Read the response body or status code afterwards.

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HTML

Semantic Article Structure

`<article>` for self-contained content (blog post, comment, news item). Each article gets its own header, body, and (optionally) footer. Helps screen readers, RSS, and Google understand structure.

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