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#php
#kotlin
#bash
#go
#sql
#rust
#typescript
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PHP
Average / Median / Mode
Three classic descriptive statistics over a numeric array. Built without any external math library — just sort + count.
@admin
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.
Go
Pipeline (channel chain)
A pipeline is a chain of stages connected by channels — each stage runs in its own goroutine. Classic Go pattern for streaming transformations with backpressure built in.
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.
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".
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".
Go
Test Helpers with t.Helper()
When you extract a verification routine into a helper, call `t.Helper()` so failure messages point to the CALLER line — not the helper line. One line, much better diagnostics.
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.
PHP
CSRF Token Generate + Verify
Per-session CSRF token helpers using hash_equals for constant-time comparison. Token is regenerated on logout but persists across requests within a session.
Kotlin
Sequences — Lazy Collections
A `List` materializes every intermediate `map`/`filter` result. A `Sequence` processes ONE element through the whole pipeline at a time — better for big inputs or short-circuiting (`first`, `take`).
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.
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.
PHP
Validate Password Strength
Score a password 0–4 (NIST-inspired, not the full zxcvbn algorithm). Encourages length over complexity; flags well-known weak patterns. Use as a UI hint, not a hard barrier.
Kotlin
Write to a File
`writeText` overwrites; `appendText` appends. For multiple writes, use `bufferedWriter().use { }` for efficiency + auto-close.
Kotlin
map / filter / reduce
The three classic functional combinators. Each takes a lambda and returns a new collection (or a single value for reduce). Chain freely — intermediate allocations only matter at very large scale (use `Sequence` then).
Rust
tokio mpsc Channel
Async multi-producer / single-consumer channel. Producers `.send()`, the single receiver `.recv().await` items as they arrive. Bounded — the channel back-pressures producers when full.
TypeScript
range — Lazy Number Iterator
A generator-based numeric range: `[start, end)` with an optional step. Lazy so it doesn't allocate a huge array up front; consume with for…of or Array.from.