Digital Digressions by Stuart Sierra
From programming to everything else
A brief addendum to my last post about Clojure’s threading macros. As I was saying … I said you could use as-> to work around the placement of an argument that doesn’t quite fit into a larger pattern of ->. My example was: (-> results :matches (as-> matches (filter winning-match? matches)) (nth 3) :scores (get…
No, not multi-threading. I’m talking about Clojure’s threading macros, better known as “the arrows.” The -> (“thread-first”) and ->> (“thread-last”) macros are small but significant innovations in Clojure’s Lisp-like syntax. They support a functional style of programming with return values and make composition intuitive. They answer the two chief complaints about Lisp syntax: too many…
How long does Clojure start-up really take? Let’s find out. Get yourself a Clojure project. Download the dependencies and pre-generate the classpath: lein deps lein classpath > cp.txt This lets us run “raw” Clojure, without any tooling. Assuming a Bash-like shell: time java -cp “$(cat cp.txt)” clojure.main -e ‘(System/exit 0)’ Now add Leiningen: time lein run…
Polymorphism is a powerful feature. The purpose of polymorphism is to provide a single, consistent interface to a caller. There may be multiple ways to carry out that behavior, but the caller doesn’t need to know that. When you call a polymorphic function, you remain blissfully ignorant of (and therefore decoupled from) which method will…
Earlier this year, I wrote a piece for the Cognitect blog: Developing the Language of the Domain (blog.cognitect.com) In it, I describe the process of building a domain-driven application using Clojure, ClojureScript, EDN, Datomic, clojure.spec, Pedestal, and Om.
Quick link: Stuart’s ns Style Guide Everyone has their own personal quirks when it comes to syntax. No matter how hard you try to lock it down with code review, IDEs, scripts, or check-in hooks, individual differences will emerge. In Clojure the situation is generally pretty stable: most people follow the same general patterns, which…
I am responsible — for better or for worse — for the library which eventually became clojure.test. It has remained largely the same since it was first added to the language distribution back in the pre-1.0 days. While there are many things about clojure.test which I would do differently now — dynamic binding, var metadata,…
Cast your mind back to the halcyon days of the late ’90s. Windows 95/98. Internet Explorer 4. Before you laugh, consider that IE4 included some pretty cutting-edge technology for the time: Dynamic HTML, TLS 1.0, single sign-on, streaming media, and “Channels” before RSS. IE4 even pioneered — unsuccessfully — the idea of “web browser as…
This is a guide on naming Clojure functions. There are exceptions to every rule. When you’re defining something based on natural language, there are more exceptions than rules. I break these rules more often than I follow them. This guide is just a starting point for thinking about how to name things. Pure functions Pure…
Another year, another year-in-review post. To be honest, I feel like any attempt I make to summarize what happened in the Clojure world this year is largely moot. Clojure has gotten so big, so — dare I say it? — mainstream that I can’t even begin to keep up with all the interesting things that…