Rewrite of a Flask Web App in Clojure

 Posted on 2025-02-22  (Last modified on 2025-03-30)  |  16 minutes  |  3212 words

Intro A few years ago, I made a simple web app in Flask to deal with some text processing problems from my daily work. It has two main features: Feature #1: generating compile_commands.json for GNU Makefile projects written in C/C++ using the output of the make command. Because, unlike CMake, the make command can't generate it. Feature #2: extract text using Python regex. It's handy when I feel like sed/awk/grep's line-oriented processing isn't enough for the task at hand. [Read More]
Clojure  ClojureScript  Reagent  shadow-cljs  Flask 

Constructing Clojure Maps Conditionally

 Posted on 2025-01-05  (Last modified on 2025-02-20)  |  1 minutes  |  190 words

I was wondering how to construct a multi-key map conditionally while I was coding in Clojure. Ideally, I would like to build it "in one pass" like {:bar 2 (when true :baz 3)}, but from what I had collected from Blue Sky, it seemed that's impossible, or it's just not an idiomatic way to program like that in Clojure. (Or, is this just a side effect of writing too much imperative code? [Read More]
clojure  tweet 

Getting Started with Cider for Clojure Programming

 Posted on 2024-12-22  |  2 minutes  |  303 words

Here is the outline for my cider tutorial on YouTube, covering basic things you need to know to get started with cider, and starting exploring the fun of clojure programming with the REPL-driven programming approach. Jack In to a REPL C-c M-j (cider-jack-in-clj) start a nREPL and jack in. It works in a project or with a sole .clj file. M-x cider-connect-clj run the command and then fill in hostname and port. [Read More]
clojure  cider  emacs 

A Few Quick Notes About babashka/fs

 Posted on 2024-12-07  (Last modified on 2024-12-19)  |  1 minutes  |  149 words

Recently I've used babashka/fs a little bit, here are some quick notes for it: Path vs File. Use Path whenever possible, according to this SO answer to "Java: Path vs File". This is actually Java related. It's ok to use a path as a key for a clojure map. At my first try, I somehow came to the conclusion that it's not ok, while I was refactoring the live reload for clay. [Read More]
clojure  cider  clay  python  tweet 

Doing Unit test in Clojure Is Easy

 Posted on 2024-11-28  (Last modified on 2025-02-26)  |  1 minutes  |  165 words

While refactoring the live reload feature of Clay, I realized I'd better break long functions into smaller and functional ones (as many as I can), which is also a common practice in the clojure community. Small pure functions not only are easy to verify on the development process (using a REPL), but also are easy to test. And unit tests are easy to write in clojure, just use deftest from clojure. [Read More]
clojure  cider  clay  tweet 

Clj-async-profiler Rocks

 Posted on 2024-11-28  (Last modified on 2025-03-09)  |  2 minutes  |  369 words

While developing the live reload feature for Clay, a minimalistic Clojure tool for data visualization and literate programming, I found that it constantly takes ~1 minute for beholder to watch a directory. After some code inspect, I was still having no idea why it happened. So I decided to use a profiler to find out what's going one under the hood, and Google immediately took me to clj-async-profiler. It's easy to set up following its basic usage docs: [Read More]
Clojure  Clay 

Adding Clojure Dependencies from the Command Line

 Posted on 2024-11-09  (Last modified on 2024-11-10)  |  1 minutes  |  84 words

While debugging a live reload issue of Clay a few days ago, I learned from Markus Agwin that we can actually add dependencies on the fly from the command line, just like this: clj -Sdeps "{:deps {org.scicloj/clay {:mvn/version \"2-beta21\"}}}". Even better, we can add dependency from a Git repo and specify the commit hash: clj -Sdeps "{:deps {io.github.scicloj/clay {:git/url \"https://github.com/scicloj/clay.git\" :git/sha \"35a46541db66ae6b4e1af628b7c24c42d3be418f\"}}}", which is really helpful for experimenting and verifying things. [Read More]
Clojure  Tweet  clj 

Bitten by Lazy Sequence of map

 Posted on 2024-11-09  (Last modified on 2024-11-10)  |  1 minutes  |  167 words

While impletenting the live reload feature for Clay a few weeks ago, unfortunately, I was bitten by the laziness of map. It seems quite obvious we all know that its result is a lazy sequence, but I just can't help fall into the "trap". At that time I was adding a vector to keep track of all beholder instances watching file changes in user specified directories. So then when it's time to stop all the watchers, I used something like to achieve the goal: [Read More]
Clojure  Tweet 

Anonymous Functions in Thread Macros

 Posted on 2024-11-08  (Last modified on 2024-11-10)  |  1 minutes  |  194 words

While adding the live reload feature to Clay, I encountered a problem of applying anonymous functions to thread macros. For example, below is a simple snippet trying to wrap the input directory as a vector with the help of thread macro, but surprisingly, it errors out. After some searching, I figured out that I need to put the anonymous function into another pair of parentheses: (-> "/tmp/" #(if (vector? %) % [%])) ;; => Syntax error (ClassCastException) compiling fn* at (simple4all. [Read More]
Clojure  Tweet 

Starting a Clojure nREPL Manually for Cider

 Posted on 2024-11-08  (Last modified on 2025-02-18)  |  1 minutes  |  174 words

While troubleshooting and fixing a live reload bug in Clay today, which required to start a minimal Clojure environment, I figured out how to start a nREPL from the command line. Instead of using M-x cider-jack-in-clj directly from Emacs, actually we can manully bring up an nREPL with this: clj -Sdeps "{:deps {org.scicloj/clay {:mvn/version \"2-beta21\"} cider/cider-nrepl {:mvn/version \"0.50.2\"}}}" -m nrepl.cmdline --middleware "[cider.nrepl/cider-middleware]" (The clay part is only necessary for this debugging), and then connect to this nREPL using the Emacs command M-x cider-connect-clj. [Read More]
Cider  Clojure  Tweet