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#php
#kotlin
#bash
#go
#sql
#rust
#typescript
#html
#java
#python
#files
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#concurrency
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#format
Kotlin
zip and zipWithIndex
`zip` pairs elements positionally; the result is the length of the shorter list. `withIndex()` gives you `(index, value)` pairs without the manual `forEachIndexed`.
@admin
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.
PHP
Resize Image to Max Dimension
Shrink an uploaded image so its longest side is no more than $maxDim pixels, preserving aspect ratio. Re-encodes to JPEG at the given quality. Uses the GD extension.
Bash
Multipart File Upload via cURL
Upload one or more files using -F. Optional extra form fields go through the same flag — quote carefully to preserve spaces.
Python
Protocol — Structural (Duck) Typing
Define what an object can DO, not what it IS. A class doesn't need to inherit from a Protocol — it just needs to match the shape. Like TypeScript interfaces with `implements` optional.
SQL
MERGE — One Statement for INSERT + UPDATE + DELETE
`MERGE` (standard SQL, PostgreSQL 15+, SQL Server, Oracle) is a single statement that combines INSERT/UPDATE/DELETE driven by joining a source against a target. Heavy artillery for reconciliation jobs.
Go
Worker Pool with Channels
Spawn N worker goroutines, feed them tasks over a jobs channel, collect results on a results channel. Idiomatic Go pattern for bounded concurrency.
Go
Empty Struct Sentinel (struct{})
`struct{}` is a zero-size value — no memory cost. Use it as the value type in a Set (`map[T]struct{}`), as a channel signal (`chan struct{}`), or as a marker type.
JavaScript
Fetch with Retry
Wraps the native fetch API with automatic retry logic using exponential backoff. Retries on network errors or non-OK HTTP responses up to a configurable number of attempts. Exponential backoff with optional jitter prevents thundering herd problems when many clients retry simultaneously.
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.
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.
Rust
impl Trait — Static Dispatch Returns
When you want to return a complex iterator chain or closure, you don't need to spell out the type. `impl Trait` lets the compiler infer the concrete type while exposing only the API contract.
Kotlin
Compose Modifier Chain
`Modifier` is how you customize composables — padding, click handlers, background, size, alignment. Order matters: each modifier wraps the previous one.
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.
Go
Error Wrapping with %w
`fmt.Errorf` with `%w` wraps an inner error inside an outer one, preserving the chain. Callers can use `errors.Is` / `errors.As` to inspect any level of the chain.
Kotlin
Sorting Collections
`sortedBy { ... }` returns a sorted copy. `sortedWith(compareBy { ... })` chains tie-breakers cleanly. Avoid `sortBy` (in-place) on read-only lists.
JavaScript
Rate Limiter (Token Bucket)
Implements a token-bucket rate limiter that allows a burst of calls up to a maximum capacity, then replenishes tokens at a steady rate. Useful for throttling outbound API requests, user-facing actions, or any operation where you need to allow occasional bursts without exceeding a sustained rate.
JavaScript
Range Generator
Generates an array of numbers from start to end (inclusive) with an optional step. Supports negative steps for counting down. Covers the most common use case of Array.from({ length: n }, (_, i) => i) with a much cleaner API, and handles arbitrary start/end/step combinations.