Clojure is difficult, but worth it.

Transcript

1. Clojure is Difficult ( ( But worth it!! ) ) Sezal Jain Nilenso
2. /11 2 • Parentheses • Debugging • For • Lazy Sequences • Lack of Examples • Interaction with db • Hon’ mention Outline
3. Parentheses • Cursive (IntelliJ), Cider(Emacs) • Structural Editing • Paredit • Slurp, barf Links http://danmidwood.com/content/2014/11/21/animated-paredit.html https://cursive-ide.com/userguide/paredit.html (- 1 (* c (+ a b) d) /11 3
4. • Repl is great. Use it! • Print debugging • hashp, log/spy • Cider Tracing, Debugger Links: https://eli.thegreenplace.net/2017/notes-on-debugging-clojure-code/ https://docs.cider.mx/cider/debugging/tracing.html Debugging (let [x 10 y 10] (if (= x y) (prn (func1 x y)) (func2 x y))) (-> [1 2 3] (map inc) (prn) (filter even?)) /11 4 (defn debug [x] (prn x) x)
5. • Repl is great. Use it! • Print debugging • hashp, log/spy • Cider Tracing, Debugger Links: https://eli.thegreenplace.net/2017/notes-on-debugging-clojure-code/ https://docs.cider.mx/cider/debugging/tracing.html Debugging (let [x 10 y 10] (if (= x y) (debug (func1 x y)) (func2 x y))) (-> [1 2 3] (map inc) (debug) (filter even?)) /11 5 (defn debug [x] (prn x) x)
6. • It’s a list comprehension • {2x | x ∈ [1 2 3 4], x2>3} • map/filter • doseq • loop/recur/reduce • multiple sequences/dimensions for /11 6
7. Lazy Sequences (do (map prn [0 1 2 3 4 5 6 7 8 9 10]) (println "Hello, world!”)) “Hello, world!” (defn slow-fn [a] (Thread/sleep 1000) (+ 1 a)) (time (slow-fn 5)) "Elapsed time: 1004.547512 msecs” (time (map #(slow-fn %) [1 2 3]) "Elapsed time: 0.116936 msecs" Be Aware!! • Lazy — for, map, filter, range • Not lazy — doall, doseq, reduce Be Aware!! /11 7
8. Lack of Examples [clojure] - 16068 • Clojurians slack, ask.clojure.org, clojure reddit • Dig into library source code • Write blogs • Ask/answer questions Severe lack of open source code [python] - 1,345,241 [ruby] 211,001 [haskell] 43,115 /11 8
9. Write migration function using ragtime etc Migrate Write crud functions for the table using jdbc Magic vs No Magic Write a Model for a new table Write sql migration for a table, add constraints etc Migrate Django Clojure Migrations are auto-created, Migrate /11 9
10. Sql knowledge a must Minimal knowledge of sql Write a Model for a new table Write sql migration for a table, add constraints etc Write migration function using ragtime etc Migrate Write crud functions for the table using JDBC Migrations are auto-created, Migrate /11 10 Magic vs No Magic
11. Snake vs Kebab k-e-b-a-b s_n_a_k_e Why?? Why?? Why?? Why?? /11 11