I'm trying to filter a [[String]] based upon a regex.

```
filter (\fn -> case (matchRegex (mkRegex "*.exe") fn) of Nothing -> False
                                                         Just _ -> True) 
       directory_info

```

Unfortunately, the lambda function is syntactically invalid here: a pattern match can not occur in expression context, according to ghc.

How should this be rephrased to concisely execute the intended meaning?