LowercasePatternMatch.md

Pattern: Lowercase pattern match

Issue: -

Description

A lower case pattern match clause with no other tokens is the same as _. This is not true for patterns which start with an upper case letter. This can cause confusion, and may not be what was intended:

val foo = "foo"
val Bar = "bar"
"bar" match { case Bar => "we got bar" }   // result = "we got bar"
"bar" match { case foo => "we got foo" }   // result = "we got foo"
"bar" match { case `foo` => "we got foo" } // result = MatchError

This rule raises a warning with the second match. To fix it, use an identifier which starts with an upper case letter (best), use case _ or, if you wish to refer to the value, add a type : Any

val lc = "lc"
"something" match { case lc: Any => "lc" } // result = "lc"
"something" match { case _ => "lc" } // result = "lc"

Example configuration

<check enabled="true" class="org.scalastyle.scalariform.LowercasePatternMatchChecker" level="warning"/>

Further Reading

• Scalastyle - LowercasePatternMatch