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
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.
@admin
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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.
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!`.
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.