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.

1h ago 0

Go

UUID Generation (google/uuid)

`github.com/google/uuid` is the standard UUID library. v4 (random) for IDs, v7 (time-ordered) when you want UUIDs that sort chronologically and play nicely with B-tree indexes.

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PHP

Compound Interest Calculator

Compute the future value of an investment compounded n times per year for t years. Returns both the final value and the interest earned.

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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.

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JavaScript

Calculate Reading Time

Estimates the reading time of a block of text based on an average adult reading speed (default 200 words per minute). Strips HTML tags before counting to handle rich-text content. Returns the result in minutes, rounded up, so a short article always shows at least "1 min read".

1h ago 0

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.

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Go

Static File Server

`http.FileServer` serves a directory; combine with `http.StripPrefix` to mount it at a URL path. One line for the most common static-asset use case.

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Go

JSON Marshal / Unmarshal

`encoding/json` is the standard library JSON parser. `Marshal` produces compact JSON; `MarshalIndent` produces pretty-printed. `Unmarshal` decodes into a typed value (struct, map, or any).

1h ago 0

Java

Generic Method + Bounded Type Parameters

A method can have its own type parameter independent of the class. `<T extends Comparable<T>>` constrains T to types that can be compared.

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PHP

Smart Title Case

Convert a string to title case while keeping common short words (a, an, the, of, etc.) lowercase — unless they appear at the start or end of the title.

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PHP

Rotating Log Writer

Append to a single log file but auto-rotate to .1/.2/.3 once the file exceeds a configurable size. No external dependencies — just rename + size check.

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PHP

Tail Last N Lines of File

Efficiently read the last N lines of a (possibly large) file by seeking to the end and walking backwards in fixed-size chunks. Avoids loading the entire file into memory.

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TypeScript

Retry with Exponential Backoff + Jitter

Retry an async operation up to N times, doubling the delay each attempt with random jitter to avoid thundering herd. Decide retryability via an optional predicate so 4xx errors stop immediately.

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Go

HTTP POST JSON Body

Build a request with `http.NewRequestWithContext`, set headers, send via your client. The context plumbing is what lets callers cancel mid-request.

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Bash

Pretty-Print Last Exit Code

A tiny prompt-trick that shows the previous command's exit code in red when it failed. Stops you from missing silent errors in long terminal sessions.

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Java

Stream.reduce — Aggregate to a Single Value

`reduce` collapses a stream to one value: sum, product, max, min, custom accumulation. Two-arg form needs an identity (zero/seed); three-arg form supports parallel streams via a combiner.

1h ago 0

Go

net/url — Build Query Strings Safely

Stop concatenating `?a=1&b=2` by hand. `url.Values` (a `map[string][]string`) escapes correctly, handles repeated keys, and `url.URL.String()` renders the canonical form.

1h ago 0

Rust

Read a File — Whole / Lines / Bytes

Three common patterns: load it all into memory, iterate line-by-line, or stream bytes. Pick by file size — `read_to_string` is convenient but bad for huge files.

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Bash

DNS Lookup (dig / host / getent)

Three options depending on what's installed: dig is most flexible, host is concise, getent uses the system's resolver and respects /etc/hosts.

1h ago 0

Kotlin

Nullable Types — String? and the ? Operator

Kotlin distinguishes `String` (never null) from `String?` (may be null) in the type system. The compiler refuses to compile code that could deref a possibly-null value — the famous "no more NullPointerException" feature.

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SQL

Recursive CTE — Walk a Hierarchy

`WITH RECURSIVE` lets a CTE refer to itself. The standard way to walk parent/child trees (org charts, comment threads, category nestings) in a single query.

1h ago 0

Go

iter.Seq — Range-Over-Func (Go 1.23+)

Go 1.23 added "range over func" — your own functions can produce values that work with `for v := range fn`. Cleaner than channels for in-process iteration without goroutine overhead.

1h ago 0

Kotlin

Safe Call Chain + Elvis Default

`?.` is the safe-call operator — short-circuits to `null` at the first null in a chain. Pair with `?:` (Elvis) for "this or a default". Replaces nested if-not-null ladders.

1h ago 0

HTML

Video Element with Captions

`<video>` with multiple `<source>` formats (MP4 + WebM), `controls`, `poster`, and a captions track via `<track kind="captions">`. All shipped with the browser — no JS player needed.

1h ago 0

Go

base64 Encode / Decode

`encoding/base64` has Standard, URL-safe, and Raw (no padding) variants. URL-safe replaces `+/` with `-_` so the output is safe in query strings and filenames.

1h ago 0

Python

Context Manager via @contextmanager

Build a custom context manager without writing a class — just a generator with one `yield`. The code before yield runs on enter, after yield runs on exit (even on exception).

1h ago 0

Rust

Async/Await with tokio

`async fn` returns a future; `.await` drives it. tokio is the de-facto runtime. The `#[tokio::main]` attribute turns `main` into the runtime entry point.

1h ago 0

SQL

Pivot Without PIVOT (Conditional Aggregation)

Most databases don't have a real `PIVOT` keyword (SQL Server does). The portable answer is conditional aggregation — `SUM(CASE WHEN ...) AS col` for each pivoted value.

1h ago 0

SQL

ROLLUP — Subtotals and Grand Totals

`GROUP BY ROLLUP` adds subtotal rows (with NULL for the rolled-up columns) plus a grand total. Drop into reports without writing UNIONs by hand.

1h ago 0

TypeScript

Environment Variable Validator

Validate process.env at boot-time and exit fast if anything's missing. The returned object is typed so the rest of the code reads `env.DATABASE_URL` instead of `process.env.DATABASE_URL!`.

1h ago 0