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#php
#kotlin
#bash
#go
#sql
#rust
#typescript
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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.
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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.
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.
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.
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.
PHP
Paginated Query Helper
Run a SELECT with LIMIT/OFFSET and also return the total row count, so you can render "Page 3 of 47" UIs. Single function, two round trips.
Rust
Atomic File Write (tempfile + persist)
Write to a temp file in the SAME directory, then atomically `persist` (rename). The `tempfile` crate handles cleanup if you crash before persisting.
PHP
Bulk INSERT in a Single Statement
Insert a list of rows in one round trip by building a multi-VALUES statement with placeholders. Orders-of-magnitude faster than looping single INSERTs.
PHP
PDO Transaction Wrapper
Run a closure inside a transaction. Commits on success, rolls back on any exception, then re-throws so the caller can react. Avoids the bug-prone copy-paste of begin/commit/rollBack.
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.
Python
Generate Strong Random Password
Build a password using the `secrets` module (CSPRNG) with rejection sampling for unbiased distribution. Use this — NOT random.choice, which is seeded predictably.
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.
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.
PHP
Business Days Between Two Dates
Count weekdays (Mon-Fri) between two dates, excluding an optional list of holidays. Direction-aware (works even if $end < $start).
PHP
cURL POST JSON
Post a JSON body with the right Content-Type header and parse the response. Returns the decoded body or throws on a non-2xx response.
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`.
Python
Async Context Manager (aiohttp pattern)
Define an async resource using `@asynccontextmanager` from contextlib. Cleaner than writing a class with __aenter__/__aexit__ for one-off wrappers.