Go

Interface Segregation — Small Interfaces

"The bigger the interface, the weaker the abstraction." Go encourages small, focused interfaces (often just one method) — io.Reader, io.Writer, fmt.Stringer. Define them at the consumer side.

1h ago 0

Go

Benchmarks with testing.B

`BenchmarkXxx(b *testing.B)` functions are run by `go test -bench`. `b.N` is the loop count the framework auto-tunes; report results in ns/op, allocs/op.

1h ago 0

HTML

RTL (Right-to-Left) Document

Set `dir="rtl"` on the root element for languages that read right-to-left (Arabic, Hebrew, Persian). The browser flips text alignment, scroll, and form controls automatically. Use `dir="auto"` to let user-generated text decide per-block.

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Kotlin

apply — Configure Object, Return Itself

`x.apply { ... }` runs the block with `x` as `this` (so you call methods/set properties directly) and returns `x`. The canonical builder-style configuration.

1h ago 0

Kotlin

Jetpack Compose — Basic Composable

Compose is Android's modern declarative UI toolkit. A `@Composable` function describes UI; the runtime re-runs it when inputs change. Replaces XML layouts entirely.

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Python

NewType for Nominal IDs

Python's type system is structural — `UserId` and `PostId` are both just `int` unless you ask otherwise. `NewType` creates a distinct type with zero runtime cost for static checking only.

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Bash

Convert Between Timezones

Set TZ inline to print a date in a specific timezone, then read with another TZ. Avoids messing with the system timezone.

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Rust

fold / reduce / scan

`fold` is the general aggregator: starts from an accumulator, applies a fn to each item. `reduce` uses the first item as the seed. `scan` yields intermediate accumulator values.

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Go

iota — Auto-Incrementing Constants (Enums)

Go has no `enum` keyword but `iota` inside a const block gives you the same effect. Each line is the previous expression with iota auto-incremented.

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Rust

Result Combinators + the ? Operator

`Result<T, E>` chains like `Option`. The `?` operator unwraps `Ok` or early-returns the `Err`, converting via `From` so callers can use one error type for many sources.

1h ago 0

Go

Custom Generic Constraints

Type constraints are interfaces with type sets. Use them to express "any numeric" or "any ordered" without resorting to `any`.

1h ago 0

TypeScript

Capitalize / Title-Case

Two common case transforms. `capitalize` for the first letter only; `titleCase` for every word, with small "stop words" left lowercase except at the edges.

1h ago 0

Python

Async Retry with Exponential Backoff

Retry an async operation up to N times, doubling the wait each attempt with random jitter to avoid thundering herd. Predicate controls retryability so 4xx errors stop immediately.

1h ago 0

Java

java.time — Instant, LocalDate, ZonedDateTime

Java 8's `java.time` package replaced the broken `Date`/`Calendar`. Three types you actually use: `Instant` (UTC moment), `LocalDate` (date with no tz), `ZonedDateTime` (date+time in a zone).

1h ago 0

Java

Stream Basics — filter / map / collect

The fluent pipeline for transforming collections. `filter` keeps matching elements, `map` transforms each one, `collect(toList())` materializes the result.

1h ago 0

Java

HttpClient — Async (CompletableFuture)

`sendAsync` returns a `CompletableFuture<HttpResponse<T>>` — chain it like any other CF. Fan out N requests, wait for all with `CompletableFuture.allOf`.

1h ago 0

HTML

Skip-to-Main-Content Link

Keyboard users (and screen-reader users) tab through every nav link before reaching content. A skip-link as the first focusable element jumps straight to <main>. Required for WCAG 2.1 AA.

1h ago 0

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.

1h ago 0

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.

1h ago 0

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.

1h ago 0

Kotlin

Generic Class and Function

`<T>` declares a type parameter. Use it on classes (`Box<T>`) and functions (`fun <T> identity(x: T) = x`). Type bounds (`T : Comparable<T>`) constrain what T can be.

1h ago 0

Bash

Find Largest Files and Directories

Quick "where did all my disk go?" answer. du sorts by size, ncdu (interactive) is better for exploration.

1h ago 0

Rust

Box<dyn Error> — Quick Boxed Errors

If you don't want the thiserror/anyhow dependency, `Box<dyn std::error::Error>` works as a catch-all. The `?` operator promotes any concrete error via `From`.

1h ago 0

HTML

Comment / Review Markup with Schema

Comments and reviews can also have Schema.org markup. The `Review` type appears under products in Google search results with star ratings; `Comment` is for general user feedback.

1h ago 0

SQL

Median with PERCENTILE_CONT

SQL has no `MEDIAN()` — use `PERCENTILE_CONT(0.5) WITHIN GROUP`. The same function gets you P95, P99, quartiles, etc. for latency analysis.

1h ago 0

Rust

Group By a Key (fold into HashMap)

No built-in `group_by`, but `fold` into a `HashMap` does the same thing in two lines — and the type system tracks keys / values correctly.

1h ago 0

Python

JWT Sign + Verify (PyJWT)

The de-facto JWT library for Python. HS256 demo with an exp claim and the standard "verify everything" decode flow. Mind that PyJWT raises specific exceptions you can catch separately.

1h ago 0

Rust

Custom Error Type with thiserror

The `thiserror` crate generates a clean `Error + Display + Debug` impl from an enum, with automatic `From` conversions. The library-author's error-type tool of choice.

1h ago 0

Java

try-with-resources

For any `AutoCloseable` (files, streams, DB connections, locks), declare it in `try(...)` and Java auto-calls `close()` even on exception. Replaces error-prone `try / finally` blocks.

1h ago 0

Java

CountDownLatch — Wait for N Events

Block one or more threads until a count of events occurs. Set the count up front; each event calls `countDown()`; waiters call `await()`. Classic "wait until all workers are ready" pattern.

1h ago 0