diff --git a/README.md b/README.md
index c4b47c2..d3f518e 100644
--- a/README.md
+++ b/README.md
@@ -34,7 +34,7 @@ filter only the errors introduced in the commit range (and nothing more).
 
   ```sh
   # This will lint the last commit
-  difflint lint --commit-range HEAD^..HEAD
+  difflint lint HEAD^..HEAD
   ```
 
 ## Examples
@@ -42,12 +42,18 @@ filter only the errors introduced in the commit range (and nothing more).
 1. Lint the last 3 commits:
 
   ```sh
-  difflint lint --commit-range HEAD~3..HEAD
+  difflint lint HEAD~3..HEAD
   ```
 
-2. Lint all commits from a build in Travis:
+2. Lint local changes that are not yet commited (similar to what [lint-staged](https://github.com/okonet/lint-staged) do):
+
+  ```sh
+  difflint lint HEAD
+  ```
+
+3. Lint all commits from a build in [Travis](https://travis-ci.org):
 
   ```sh
   # This environment variable will be available in any Travis build
-  difflint lint --commit-range $TRAVIS_COMMIT_RANGE
+  difflint lint $TRAVIS_COMMIT_RANGE
   ```
diff --git a/src/difflint.js b/src/difflint.js
new file mode 100644
index 0000000..7bd413c
--- /dev/null
+++ b/src/difflint.js
@@ -0,0 +1,109 @@
+import Promise from 'bluebird'
+import exec from 'execa'
+import path from 'path'
+import { CLIEngine } from 'eslint'
+import {
+  T,
+  assoc,
+  cond,
+  curry,
+  curryN,
+  endsWith,
+  evolve,
+  equals,
+  filter,
+  find,
+  map,
+  objOf,
+  pipe,
+  pipeP,
+  pluck,
+  prop,
+  propEq,
+  split,
+  sum,
+  tap,
+} from 'ramda'
+import { getChangedLinesFromDiff } from './lib/git'
+
+const linter = new CLIEngine()
+const formatter = linter.getFormatter()
+
+const getChangedFiles = pipeP(
+  commitRange => exec('git', ['diff', commitRange, '--name-only']),
+  prop('stdout'),
+  split('\n'),
+  filter(endsWith('.js')),
+  map(path.resolve)
+)
+
+const getDiff = curry((commitRange, filename) =>
+  exec('git', ['diff', commitRange, filename])
+    .then(prop('stdout')))
+
+const getChangedFileLineMap = curry((commitRange, filePath) => pipeP(
+  getDiff(commitRange),
+  getChangedLinesFromDiff,
+  objOf('changedLines'),
+  assoc('filePath', filePath)
+)(filePath))
+
+const lintChangedLines = pipe(
+  map(prop('filePath')),
+  linter.executeOnFiles.bind(linter)
+)
+
+const filterLinterMessages = changedFileLineMap => (linterOutput) => {
+  const filterMessagesByFile = (result) => {
+    const fileLineMap = find(propEq('filePath', result.filePath), changedFileLineMap)
+    const changedLines = prop('changedLines', fileLineMap)
+
+    const filterMessages = evolve({
+      messages: filter(message => changedLines.includes(message.line)),
+    })
+
+    return filterMessages(result)
+  }
+
+  return pipe(
+    prop('results'),
+    map(filterMessagesByFile),
+    objOf('results')
+  )(linterOutput)
+}
+
+const applyLinter = changedFileLineMap => pipe(
+  lintChangedLines,
+  filterLinterMessages(changedFileLineMap)
+)(changedFileLineMap)
+
+const logResults = pipe(
+  prop('results'),
+  formatter,
+  console.log
+)
+
+const getErrorCountFromReport = pipe(
+  prop('results'),
+  pluck('errorCount'),
+  sum
+)
+
+const exitProcess = curryN(2, n => process.exit(n))
+
+const reportResults = pipe(
+  tap(logResults),
+  getErrorCountFromReport,
+  cond([
+    [equals(0), exitProcess(0)],
+    [T, exitProcess(1)],
+  ])
+)
+
+const run = commitRange => Promise.resolve(commitRange)
+  .then(getChangedFiles)
+  .map(getChangedFileLineMap(commitRange))
+  .then(applyLinter)
+  .then(reportResults)
+
+export default run
diff --git a/src/index.js b/src/index.js
index 7c46963..955cf24 100644
--- a/src/index.js
+++ b/src/index.js
@@ -1,91 +1,8 @@
-import Promise from 'bluebird'
-import exec from 'execa'
 import program from 'commander'
-import path from 'path'
-import { CLIEngine } from 'eslint'
-import {
-  assoc,
-  curry,
-  endsWith,
-  evolve,
-  filter,
-  find,
-  map,
-  objOf,
-  pipe,
-  pipeP,
-  prop,
-  propEq,
-  split,
-} from 'ramda'
-import { getChangedLinesFromDiff } from './lib/git'
-
-const linter = new CLIEngine()
-const formatter = linter.getFormatter()
-
-const getChangedFiles = pipeP(
-  commitRange => exec('git', ['diff', commitRange, '--name-only']),
-  prop('stdout'),
-  split('\n'),
-  filter(endsWith('.js')),
-  map(path.resolve)
-)
-
-const getDiff = curry((commitRange, filename) =>
-  exec('git', ['diff', commitRange, filename])
-    .then(prop('stdout')))
-
-const getChangedFileLineMap = curry((commitRange, filePath) => pipeP(
-  getDiff(commitRange),
-  getChangedLinesFromDiff,
-  objOf('changedLines'),
-  assoc('filePath', filePath)
-)(filePath))
-
-
-const lintChangedLines = pipe(
-  map(prop('filePath')),
-  linter.executeOnFiles.bind(linter)
-)
-
-const filterLinterMessages = changedFileLineMap => (linterOutput) => {
-  const filterMessagesByFile = (result) => {
-    const fileLineMap = find(propEq('filePath', result.filePath), changedFileLineMap)
-    const changedLines = prop('changedLines', fileLineMap)
-
-    const filterMessages = evolve({
-      messages: filter(message => changedLines.includes(message.line)),
-    })
-
-    return filterMessages(result)
-  }
-
-  return pipe(
-    prop('results'),
-    map(filterMessagesByFile),
-    objOf('results')
-  )(linterOutput)
-}
-
-const applyLinter = changedFileLineMap => pipe(
-  lintChangedLines,
-  filterLinterMessages(changedFileLineMap)
-)(changedFileLineMap)
-
-const reportResults = pipe(
-  prop('results'),
-  formatter
-)
-
-const run = commitRange => Promise.resolve(commitRange)
-  .then(getChangedFiles)
-  .map(getChangedFileLineMap(commitRange))
-  .then(applyLinter)
-  .then(reportResults)
-  .tap(console.log)
+import run from './difflint'
 
 program
-  .command('lint <commit_range>')
+  .command('lint <commit-range>')
   .action(run)
 
 program.parse(process.argv)