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#php
#kotlin
#bash
#go
#sql
#rust
#typescript
#html
#java
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#files
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#dates
#format
Python
group_by — Group Items by a Key
A dict-returning groupby that doesn't require sorted input. Like itertools.groupby but materializes the groups so consumers can iterate them multiple times.
@admin
TypeScript
JSON POST Helper
Companion to `http<T>` — POST a JSON body and parse a JSON response, both typed. Handles the boilerplate Content-Type header and JSON serialization.
HTML
HTML5 Document Boilerplate
Sensible HTML5 starting template: UTF-8 charset, responsive viewport, language attribute, semantic landmarks. Drop this in every new project before adding anything else.
Java
Optional — Stop Returning Null
`Optional<T>` makes "may be absent" part of the type signature so callers can't forget the null check. `map`, `orElse`, `ifPresent` chain naturally — no `if (x != null)` boilerplate.
Java
Collectors.toMap with Merge Function
`toMap` builds a `Map<K, V>` from a stream. The 3-arg form takes a merge function for handling duplicate keys — without it, duplicates throw IllegalStateException.
Go
time.Format — The Reference Time
Go's time formatting uses a reference date instead of strftime tokens: `Mon Jan 2 15:04:05 MST 2006` (which is 01/02 03:04:05PM '06 -0700, or 1/2/3/4/5/6/7 — mnemonic). Strange at first, instantly memorable.
Bash
Prune Dangling Docker Images
Reclaim disk space from Docker. `prune` operates on stopped containers, dangling images, build cache, and unused networks. Run periodically on CI runners.
Bash
Wait For Docker Container to Be Healthy
docker-compose entrypoints often need to wait for a sibling service (DB, cache) to be healthy before starting work. Poll the health-check status until healthy or timeout.
Bash
Check If Port Is Open
Several ways to probe a remote port: nc (most portable), bash's /dev/tcp pseudo-device (zero deps), or curl. Pick by what's available.
Python
TypedDict for JSON API Shapes
When you parse JSON, you want types — but creating a class for every payload is overkill. TypedDict gives you the static-checking benefits without the runtime overhead, and `total=False` marks every field optional.
TypeScript
safeJsonParse — Result-Typed
Parse JSON without ever throwing. Returns a Result-like discriminated union so callers must handle both success and failure paths at compile time.
PHP
Recursive Deep Merge
Merge two associative arrays at any nesting depth — like array_merge_recursive, but later values OVERWRITE earlier ones at the leaf level instead of combining them into arrays. Perfect for config-file overrides.
Kotlin
Infix Functions
A single-arg method/extension can be called without dot or parens when marked `infix`. Lets you write DSL-style code like `5 shouldBe 5` or `key to value`.
Java
Custom Exception Hierarchy
For library/service code, define a small exception hierarchy rooted at a common base class. Callers can catch the base type or specific subclasses; you can add fields for structured context.
Java
Stream.generate / iterate — Infinite Streams
Build streams from a seed + a function. `generate(supplier)` calls the supplier each time; `iterate(seed, next)` applies a unary op. Always pair with `limit` to bound them.
Rust
Iterator Chain — map / filter / collect
Rust iterators are lazy and zero-cost. Chain transformations and finally collect into a concrete container. The compiler unrolls the whole pipeline into a tight loop.
Bash
Tail Logs from Multiple Containers
`docker compose logs -f` already does this — but the one-liner with --tail and filters is the more useful day-to-day workflow when you only care about recent activity from a subset of services.