Coldwast wrote
Aug 7, 2026 in Cron, Scheduling, Unix - A cron expression is five fields and a command. Most of it is obvious. The part that is not, and that silently runs jobs on days you never intended, is what happens when you fill in both day-of-month and day-of-week.
Read more…Coldwast wrote
Aug 6, 2026 in Regex, Text Processing, Security - A regular expression is a small language for describing shapes of text. What the common symbols mean, why the same pattern behaves differently across languages, and the catastrophic backtracking case that turns a harmless-looking regex into an outage.
Read more…Coldwast wrote
Aug 5, 2026 in Cloud, Architecture, Deployment - Serverless does not mean there is no server. It means you do not provision, patch or size one. What it actually removes, how per-invocation billing works, the constraints the pitch leaves out, and the traffic level where a plain VPS costs less.
Read more…Coldwast wrote
Aug 4, 2026 in Haskell, Cabal, Build - Adding a package to a Haskell project means editing build-depends in the .cabal file. What the field expects, what the caret operator really means under the Package Versioning Policy, and why cabal update matters before anything else.
Read more…Coldwast wrote
Aug 2, 2026 in WebAssembly, Compilers, Web - WebAssembly is a binary instruction format for a stack-based virtual machine, and a portable compilation target for other languages. What the official definition says, the four design goals, and why it was never limited to the browser.
Read more…Coldwast wrote
Jul 21, 2026 in Programming, Data Structures - A linked list stores a sequence as a chain of nodes, where each node holds a value and a pointer to the next one. How singly and doubly linked lists work, how they compare to arrays, the real complexities, and when to reach for one.
Read more…Coldwast wrote
Jul 18, 2026 in Programming, Web, Performance - A CDN caches your static content on servers spread around the world so visitors get it from a nearby machine. How the edge, cache hit and miss, TTL and invalidation work, static vs dynamic, and where a CDN fits with your host.
Read more…Coldwast wrote
Jul 16, 2026 in Programming, Data Structures - A hash table stores key-value pairs and finds any value by its key in roughly constant time. How the hash function and buckets work, how collisions are handled, the real complexity, and why dictionaries are built on it.
Read more…Coldwast wrote
Jul 14, 2026 in Programming, Algorithms - Big O notation describes how an algorithm slows down as the input grows. The common complexities from O(1) to O(n!), why constants are dropped, real examples, and how to reason about the performance of your own code.
Read more…Coldwast wrote
Jul 13, 2026 in Security, Docker - A critical authentication bypass in the official Gitea Docker image (CVE-2026-20896, CVSS 9.8) is under active exploitation. What the flaw is, who is actually affected, and the exact steps to check and fix a self-hosted Gitea.
Read more…Coldwast wrote
Jul 10, 2026 in Open Source, Supply Chain - Much of the modern software stack rests on small open-source projects run by one or two unpaid people. What xkcd 2347, Heartbleed, Log4Shell and the xz-utils backdoor teach about single-maintainer risk, and what teams can actually do about it.
Read more…Coldwast wrote
Jul 9, 2026 in Programming, Architecture, Backend - A message queue is a buffer between services: one part of your app drops off a task and another picks it up later. Producers vs consumers, pub/sub, delivery guarantees, and RabbitMQ vs Kafka vs Redis.
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GHC, Cabal, Stack and HLS in one clean setup with GHCup.
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Sandboxes, nix-style v2-builds and what actually changed.
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