SQL

Moving Average (Window Frame)

Add a frame clause (`ROWS BETWEEN N PRECEDING AND CURRENT ROW`) to compute moving averages, sliding sums, rolling stats — anything that needs a bounded look-back.

5d ago 0

Java

Switch Expressions (Java 14+)

`switch` is now also an expression — it returns a value. Use `->` arrows for fall-through-free arms; `yield` inside `{ }` blocks for multi-statement arms. No more accidental forgotten `break`.

5d ago 0

Python

Producer / Consumer Queue (threading)

Classic producer / multi-consumer pattern using queue.Queue. Producers put work onto the queue; consumers pull and process; a sentinel value signals shutdown.

5d ago 0

Kotlin

require / check / requireNotNull

Three contract-style assertions in the stdlib: `require` for inputs (throws `IllegalArgumentException`), `check` for state (throws `IllegalStateException`), `requireNotNull` returns the value smart-cast.

5d ago 0

JavaScript

Validate Email Address

Validates an email address using a battle-tested regex that covers the vast majority of real-world addresses without being overly strict. For server-side code, pair this with a confirmation email step — client-side regex alone is not a security measure. Returns a boolean for easy conditional use.

5d ago 0

Go

Sentinel Errors (var ErrFoo = errors.New)

Sentinel errors are package-level singletons you can compare against with `errors.Is`. Use sparingly — they're part of your package's API surface and changing them is a breaking change.

5d ago 0

SQL

RANK / DENSE_RANK

`RANK` leaves gaps after ties (1, 2, 2, 4); `DENSE_RANK` doesn't (1, 2, 2, 3). `ROW_NUMBER` is always unique. Pick by what tied rows should produce.

5d ago 0

Go

regexp.MustCompile + FindAll

`regexp.MustCompile` panics on a bad pattern at startup — perfect for package-level vars. Use `Find`, `FindString`, `FindAllStringSubmatch` to extract matches and capture groups.

6d ago 0

JavaScript

Generate Initials Avatar (Canvas)

Draws a coloured circular avatar with up to two initials on an HTML5 Canvas and returns it as a data URL. Generates a consistent background colour from the name string so the same user always gets the same colour. Useful as a fallback when a user has no profile photo.

6d ago 0

SQL

NTILE — Bucket Rows into N Buckets

Assign rows to N approximately-equal-sized buckets based on the ORDER BY. The standard way to compute quartiles, deciles, or any percentile bucket.

6d ago 0

Kotlin

Extension Functions

Add methods to ANY type — including stdlib types like String, List, or Int — without subclassing. Compiled as a static dispatched function, so no runtime overhead.

6d ago 0

JavaScript

Parse URL Query String

Parses a URL query string into a plain key-value object. Uses the built-in URLSearchParams API — no regex required. Handles duplicate keys (returns the first value), percent-encoded characters, and works with both full URLs and raw query strings. Pairs nicely with buildQueryString.

Jun 20, 2026 0

Java

var — Local Type Inference (Java 10+)

`var` for local variables lets the compiler infer the type from the initializer. Reduces noise when the type is obvious from context — but you still get static typing.

Jun 20, 2026 0

PHP

Slack Incoming-Webhook Notification

Fire a quick notification to a Slack channel via an incoming webhook URL. Includes basic markdown-style mentions and an attachment color for severity.

Jun 20, 2026 0

Kotlin

Operator Overloading

Specially-named methods or extensions get operator syntax: `plus → +`, `minus → -`, `times → *`, `get → []`, `invoke → ()`, `contains → in`. Use sparingly for types that have natural arithmetic semantics.

Jun 20, 2026 0

Rust

Lifetime Annotations Basics

Lifetimes are how Rust proves references don't outlive what they point to. Most are inferred — but functions returning references from arguments need explicit `'a` to relate input and output.

Jun 20, 2026 0

Java

Pattern Matching for instanceof (Java 16+)

Combine `instanceof` with a variable binding — no separate cast needed. Eliminates the most common "check then cast" bug pattern and is significantly less verbose.

Jun 20, 2026 0

JavaScript

Retry Promise with Backoff

Retries a Promise-returning function up to a specified number of times with configurable exponential backoff and optional jitter. Accepts a shouldRetry predicate so you can skip retries on specific error types (e.g. 401 Unauthorized). Returns the resolved value or re-throws the last error after exhausting retries.

Jun 20, 2026 0

PHP

Discord Webhook Notification

Same idea as Slack but for Discord webhooks — supports rich embeds with a title, description, and color. Useful for dev/ops dashboards or bot integrations.

Jun 20, 2026 0

Bash

Symlink Force-Update

`ln -s` fails if the target already exists. `ln -sf` is the idempotent variant — useful in deploy scripts that point a "current" symlink to a fresh release directory.

Jun 20, 2026 0

Kotlin

Pair, Triple, and to() Infix

`Pair<A,B>` and `Triple<A,B,C>` are stdlib lightweight tuples. The `to` infix returns a Pair — used everywhere for map literals.

Jun 19, 2026 0

Go

goroutine + sync.WaitGroup

`go fn()` spawns a goroutine. To wait for several to finish, use `sync.WaitGroup` — call `Add` before spawning, `Done` (deferred) inside, `Wait` to block until all are done.

Jun 19, 2026 0

SQL

INSERT … SELECT — Bulk Copy

Copy/transform rows from a SELECT into another table — the cheapest way to move data within the database. Skip column lists at your peril; positional matching is fragile.

Jun 19, 2026 0

Rust

Enum with Data + match

Rust enums are full sum types — each variant can carry its own data. `match` is exhaustive: leave a variant unhandled and the compiler refuses to build.

Jun 19, 2026 0

SQL

COALESCE / NULLIF — Null Handling

`COALESCE(a, b, c)` returns the first non-NULL value — perfect for fallbacks. `NULLIF(a, b)` returns NULL when a equals b — handy for "treat sentinel as null".

Jun 19, 2026 0

SQL

Correlated Subquery

A subquery that references the outer query's row. Slower than a JOIN for big result sets but sometimes the most readable expression.

Jun 19, 2026 0

Java

Text Blocks (Java 15+)

Multi-line string literals with proper indentation handling. Stop concatenating newlines by hand. The compiler removes the common leading whitespace automatically.

Jun 19, 2026 0

Go

embed — Compile Assets into the Binary

Go 1.16+ `embed` lets you bundle static files (templates, web assets, SQL migrations) directly into the compiled binary — no companion files to ship.

Jun 19, 2026 0

HTML

Responsive Table — Scroll on Mobile

Wrap any wide table in a horizontally-scrolling container. The table itself stays semantic (no display:block hacks that break screen readers); only the wrapper scrolls.

Jun 18, 2026 0

Java

ConcurrentHashMap — Thread-Safe Map

The default thread-safe map. Better than `Collections.synchronizedMap` — segmented locking allows multiple readers AND writers. Use `compute`, `merge`, `putIfAbsent` for atomic compound updates.

Jun 18, 2026 0