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Is there anyone actively using Clojure in HK? Or maybe anyone who would like to use it at work?


I've done some small projects in the past few months in Clojure again and I would be interested in discussing the latest Clojure news or maybe trying out some libraries together, stuff like that... For example I was doing some web scraping with clj-soup and pumped the cleaned up results into an MS SQL server, using seancorfield/next.jdbc. I never touched any MS SQL servers before, ever in my life, so I was pleasantly surprised how seamless the experience was. It wasn't easy to find next.jdbc though; I had to practically discover the whole evolution of JDBC and its various Clojure interfaces/wrappers... Then, just the other week I saw something about


Then I've done some work with JSON, CSV/TSV files and their state is pretty messy too. I was especially surprised how big the performance differences are between various implementations. Eg. with the org.clojure/data.csv and org.clojure/data.json libs it might take several seconds to read files on the 10MB size-range, but with alternatives, like clojure-csv + semantic-csv and metosin/jsonista it takes sub-second to decode the same files.


Working with TOML files are even worse. Reading a 1.7MB TOML file with the toml library took 8 seconds. Writing a TOML in a specific format was also on the seconds range. I've ended up using org.tomlj/tomlj directly and just tailored it to the specifics of my data, to achieve reasonable performance...

(ns ...
  (:import (org.tomlj Toml)))

(defn map-vals [f m] (reduce-kv #(assoc %1 %2 (f %3)) {} m))

(defn decode
  "NOTE: Only supports 2-level nested maps with string leaf-values"
  [^String toml-str]
  (->> toml-str Toml/parse
       .toMap (into {})
       (map-vals #(into {} (.toMap %)))))


I was also looking for some consistent way to control the serialisation of CSV/TSV, EDN, JSON, TOML. I was expecting to find some generic approach, which allows me to control line wrapping and choosing between string representations and map key conversions, but every library has their own approaches... 😕 I know there is but it's not the most straight-forward things to use