Clojure Linters

clojure-linters.md

Clojure Linters

---

Self-introduction

lagénorhynque /laʒenɔʁɛ̃k/ カマイルカ

(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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cljfmt

formatter

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What's the problem?

(when something
  (something-else)
)

---

$ lein cljfmt check

 (when something
-  (something-else)
-)
+  (something-else))

---

What's the problem?

(when something
    something-else)

---

$ lein cljfmt check

 (when something
-    something-else)
+  something-else)

---

What's the problem?

(filter even?
  (range 1 10))

---

$ lein cljfmt check

 (filter even?
-  (range 1 10))
+        (range 1 10))

---

What's the problem?

(if something
    ala
    bala)

---

$ lein cljfmt check

 (if something
-    ala
-    bala)
+  ala
+  bala)

---

What's the problem?

(or
  ala
  bala
  portokala)

---

$ lein cljfmt check

 (or
-  ala
-  bala
-  portokala)
+ ala
+ bala
+ portokala)

---

eastwood

linter

---

What's the problem?

(ns linting-example.eastwood-target
  (:use [clojure.string]))

---

$ lein eastwood

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

---

What's the problem?

(if-let [x []]
  (conj x 42)
  :falsy)

---

$ 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)

---

What's the problem?

(defn f [x]
  (def y (* x x))
  (+ y 2))

---

$ lein eastwood

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

---

What's the problem?

(defn g [x]
  "blah blah blah."
  (* x x))

---

$ 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."

---

What's the problem?

(defn h [str]
  (str "Hello, " str "!"))

---

$ lein eastwood

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

---

kibit

idiom checker

---

What's the problem?

(defn add-one [x]
  (+ x 1))

---

$ lein kibit

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

---

What's the problem?

(defn check-if-zero? [x]
  (== x 0))

---

$ lein kibit

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

---

What's the problem?

(defn zip-with-* [xs ys]
  (map #(* %1 %2) xs ys))

---

$ lein kibit

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

---

What's the problem?

(defn coll->vec [coll]
  (into [] coll))

---

$ lein kibit

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

---

What's the problem?

(defn flat-map [f coll]
  (apply concat (map f coll)))

---

$ 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

---

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 <opts> && lein kibit
= lein do cljfmt check, eastwood <opts>, kibit
= lein lint  # alias as `lint`

---

$ 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

start-presentation.sh

#!/usr/bin/env bash

# npm install -g reveal-md

reveal-md clojure-linters.md --theme night --highlight-theme monokai-sublime $@