Tags
#php
#kotlin
#bash
#go
#sql
#rust
#typescript
#html
#java
#python
#files
#utils
#strings
#http
#concurrency
#async
#json
#arrays
#security
#types
#crypto
#database
#dates
#format
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.
@admin
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.
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.
Rust
match with Guards, Ranges, and Bindings
`match` arms can have `if` guards, range patterns (`1..=5`), bindings (`x @ pattern`), and ORs (`A | B`). Combine them for very expressive dispatch.
Kotlin
Smart Casts
After a successful `is` check (or null check), the compiler "smart-casts" the variable to the narrower type in that scope. No explicit cast needed.
Python
Retry Decorator with Exponential Backoff
Generic retry decorator: attempts × base delay, exponential ramp, random jitter. Filter retryable exceptions via the `on` tuple so logical errors aren't retried.
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.
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.
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.
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.
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).
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.
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.
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.
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.
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.
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.