New rule: No Single Clause Case Statements

[elbrujohalcon]

No Single Clause Case Statements

Brief Description

The following code…

case do:something() of
    {ok, Result} -> do:something(else)
end

…should actually be written using pattern-matching:

{ok, Result} = do:something(),
do:something(else)

The case statement is unnecessary and the only difference between the two is that the exception raised in the case of error changes from case_clause to badmatch.

Should be on by default?

YES

Options

• None.

Reasoning

Paraphrasing Elm-Review documentation:

[…] single-pattern case expressions […] may be written more concisely or removed entirely.

Origin (#281)

Inspired by the NoSinglePatternCase rule from elm-review

[paulo-ferraz-oliveira]

Should there be an equivalent to maybe?

[elbrujohalcon]

Probably… I had not thought much about maybe yet… mostly because I had never used it yet. 🤷🏻
But feel free to write another ticket for that rule.