Aha! Thanks, Kiss! On Tue, Apr 5, 2016 at 1:24 PM, Adam Bergmark wrote:

The regex-compat docs say "Returns: Just https://hackage.haskell.org/packages/archive/base/4.5.0.0/doc/html/Data-Mayb... strs if the match succeeded (and strs is the list of subexpression matches), or Nothing https://hackage.haskell.org/packages/archive/base/4.5.0.0/doc/html/Data-Mayb... otherwise.”.

Adam Bergmark

On Tue 05 Apr 2016 at 22:16 Jeffrey Brown > wrote:

...

Esteemed Haskellers,

It is working for me, but I am puzzled by the matchRegex function:

> import Text.Regex > :i matchRegex matchRegex :: Regex -> String -> Maybe [String] -- Defined in ‘Text.Regex’

Searches that fail return Nothing:

> matchRegex (mkRegex "z") "abracadabra" Nothing

which makes sense. But why do searches that succeed return an empty list of Strings?

> matchRegex (mkRegex "a") "abracadabra" Just [] >

-- Jeffrey Benjamin Brown

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-- Jeffrey Benjamin Brown