I don’t know about you, but I keep making typos like crazy1, so I’m really glad that today we’ve got so many tools to help us with their discovery and mitigation. While most text editors have some spell checking for the comments in source files2, that generally is not enough to free our source files from typos - often we’d make typos in identifiers, some team mates won’t be using spell checkers at all, some people would use British spellings instead of US spellings and so on.

Recently I found a really nice tool called misspell that really helps with solving such problems. It’s written in Go and is super fast. The basic usage is fairly simple3:

cider git:(master) $ misspell .
cider-debug.el:724:22: "untill" is a misspelling of "until"
cider-macroexpansion.el:47:55: "refered" is a misspelling of "referred"
cider-macroexpansion.el:48:32: "refered" is a misspelling of "referred"
CHANGELOG.md:927:9: "ouput" is a misspelling of "output"
cider-resolve.el:98:18: "referal" is a misspelling of "referral"
cider-resolve.el:99:33: "referal" is a misspelling of "referral"
cider-repl-history.el:414:32: "highlighed" is a misspelling of "highlighted"
cider-repl-history.el:421:33: "highlighed" is a misspelling of "highlighted"
cider-repl-history.el:429:36: "highlighed" is a misspelling of "highlighted"
cider-repl-history.el:434:32: "highlighed" is a misspelling of "highlighted"
cider-repl-history.el:574:3: "udpated" is a misspelling of "updated"
cider-repl-history.el:644:51: "highlighed" is a misspelling of "highlighted"
cider-stacktrace.el:656:27: "occuring" is a misspelling of "occurring"
nrepl-client.el:178:3: "Auxillary" is a misspelling of "Auxiliary"

It’s not easy to see this, but misspell found typos in both comments and source code identifiers. By default misspell allows both British and US spellings, but you can be more specific about your preference:

cider git:(master) $ misspell -locale US *.el
cider-cheatsheet.el:341:60: "cancelled" is a misspelling of "canceled"
cider-completion.el:179:52: "recognised" is a misspelling of "recognized"
cider-completion.el:181:36: "recognised" is a misspelling of "recognized"
cider-debug.el:47:20: "behaviour" is a misspelling of "behavior"
cider-inspector.el:42:20: "behaviour" is a misspelling of "behavior"
cider-eval.el:80:27: "behaviour" is a misspelling of "behavior"
cider-util.el:659:52: "cheque" is a misspelling of "check"
nrepl-client.el:427:15: "behaviour" is a misspelling of "behavior"
nrepl-client.el:567:46: "synchronise" is a misspelling of "synchronize"

I’m one of those people who learned English with British textbooks and for me that’s a mega useful feature, as I constantly opt for the British spellings, even though I know in Computer Science we’re not supposed to use them.

misspell can also fix the typos it finds, which is a huge time saver:

cider git:(master) $ misspell -w -locale US doc
doc/configuration/eldoc.md:25:0: corrected "behaviour" to "behavior"
doc/configuration/eldoc.md:33:4: corrected "behaviour" to "behavior"
doc/configuration/eldoc.md:35:36: corrected "Behaviour" to "Behavior"
doc/configuration/basic_configuration.md:85:0: corrected "behaviour" to "behavior"
doc/faq.md:49:38: corrected "favourite" to "favorite"
doc/clojurescript.md:183:32: corrected "favour" to "favor"
doc/clojurescript.md:221:4: corrected "favourite" to "favorite"
doc/repl/configuration.md:6:59: corrected "behaviour" to "behavior"
doc/repl/configuration.md:90:22: corrected "behaviour" to "behavior"
doc/repl/configuration.md:137:57: corrected "behaviour" to "behavior"
doc/repl/configuration.md:153:9: corrected "behaviour" to "behavior"
doc/repl/configuration.md:156:33: corrected "behaviour" to "behavior"
doc/repl/configuration.md:156:69: corrected "behaviour" to "behavior"
doc/repl/configuration.md:182:35: corrected "behaviour" to "behavior"
doc/repl/configuration.md:239:48: corrected "behaviour" to "behavior"

Like most such tools it’s not super reliable (meaning you’ll get some false positives here and there), but it has been very useful to me overall. If you’re an extra diligent person you can easily add it to your CI build and ensure that all typos are properly accounted for. The project’s FAQ is full of useful tips to get the most of misspell, so I encourage you to check it out.

That’s all I have for you today. Now let’s eradicate some nasty typos!

  1. Especially in blog posts. ↩

  2. https://emacsredux.com/blog/2019/05/24/spell-checking-comments/ ↩

  3. The examples are using this project https://github.com/clojure-emacs/cider. ↩