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Clojure Linters

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Self-introduction /laʒenɔʁɛ̃k/ カマイルカ lagénorhynque (defprofile lagénorhynque :name "Kent OHASHI" :languages [Clojure Haskell Python Scala English français Deutsch русский] :interests [programming language-learning mathematics] :contributing [github.com/japan-clojurians/clojure-site-ja])

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「Clojureをプロダクトに導⼊した話」

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1. cljfmt: formatter 2. eastwood: linter 3. kibit: idiom checker 4. Example Usage 5. Other Tools

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formatter cljfmt

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What's the problem? (when something (something-else) )

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$ lein cljfmt check (when something - (something-else) -) + (something-else))

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What's the problem? (when something something-else)

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$ lein cljfmt check (when something - something-else) + something-else)

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What's the problem? (filter even? (range 1 10))

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$ lein cljfmt check (filter even? - (range 1 10)) + (range 1 10))

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What's the problem? (if something ala bala)

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$ lein cljfmt check (if something - ala - bala) + ala + bala)

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What's the problem? (or ala bala portokala)

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$ lein cljfmt check (or - ala - bala - portokala) + ala + bala + portokala)

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linter eastwood

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What's the problem? (ns linting-example.eastwood-target (:use [clojure.string]))

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$ lein eastwood src/linting_example/eastwood_target.clj:2:10: unlimited-use: Unl imited use of ([clojure.string]) in linting-example.eastwood-tar get

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What's the problem? (if-let [x []] (conj x 42) :falsy)

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$ lein eastwood src/linting_example/eastwood_target.clj:4:1: constant-test: Test expression is always logical true or always logical false: [] in form (if temp__5455__auto__ (clojure.core/let [x temp__5455__aut o__] (conj x 42)) :falsy)

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What's the problem? (defn f [x] (def y (* x x)) (+ y 2))

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$ lein eastwood src/linting_example/eastwood_target.clj:9:8: def-in-def: There i s a def of y nested inside def f

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What's the problem? (defn g [x] "blah blah blah." (* x x))

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$ lein eastwood src/linting_example/eastwood_target.clj:12:7: misplaced-docstrin gs: Possibly misplaced docstring, g src/linting_example/eastwood_target.clj:12:1: unused-ret-vals: C onstant value is discarded: "blah blah blah."

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What's the problem? (defn h [str] (str "Hello, " str "!"))

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$ lein eastwood src/linting_example/eastwood_target.clj:17:3: local-shadows-var: local: str invoked as function shadows var: #'clojure.core/str

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idiom checker kibit

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What's the problem? (defn add-one [x] (+ x 1))

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$ lein kibit At src/linting_example/kibit_target.clj:4: Consider using: (inc x) instead of: (+ x 1)

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What's the problem? (defn check-if-zero? [x] (== x 0))

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$ lein kibit At src/linting_example/kibit_target.clj:7: Consider using: (zero? x) instead of: (== x 0)

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What's the problem? (defn zip-with-* [xs ys] (map #(* %1 %2) xs ys))

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$ lein kibit At src/linting_example/kibit_target.clj:null: Consider using: * instead of: #(* %1 %2)

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What's the problem? (defn coll->vec [coll] (into [] coll))

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$ lein kibit At src/linting_example/kibit_target.clj:13: Consider using: (vec coll) instead of: (into [] coll)

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What's the problem? (defn flat-map [f coll] (apply concat (map f coll)))

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$ lein kibit At src/linting_example/kibit_target.clj:16: Consider using: (mapcat f coll) instead of: (apply concat (map f coll))

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Example Usage

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e.g. ↓↓↓ lagenorhynque/situated-program- challenge/rest-server/project.clj :plugins [[jonase/eastwood "0.2.5"] [lein-cljfmt "0.5.7"] [lein-kibit "0.1.6"]] :aliases {"lint" ^{:doc "Execute cljfmt check, eastwood and kibit."} ["do" ["cljfmt" "check"] ["eastwood" "{:source-paths [\"src\"]}"] ["kibit"]]} lein cljfmt check && lein eastwood && lein kibit = lein do cljfmt check, eastwood , kibit = lein lint # alias as `lint`

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$ lein lint All source files formatted correctly == Eastwood 0.2.5 Clojure 1.9.0 JVM 9.0.1 Directories scanned for source files: src test == Linting rest-server.util == == Linting rest-server.boundary.db.core == == Linting rest-server.boundary.db.group == ... == Linting rest-server.handler.venue-test == == Linting rest-server.handler.meetup-test == == Linting rest-server.handler.member-test == == Warnings: 0 (not including reflection warnings) Exceptions thrown: 0

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Other Tools

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dependency lein deps :tree lein-ancient

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namespace slamhound

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dead code Yagni

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vulnerability lein-nvd

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test coverage cloverage

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misc. lein-bikeshed

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Utilise linters for clean Clojure code!

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Further Reading Clojure Code Quality Tools My Clojure Toolchain: Leiningen Automating Style In Clojure The state of code quality tools in Clojure clojure-style-guide