[Haskell-cafe] Pattern matching on lazy bytestrings: how does it work?

I noticed today that I can pattern match against lazy bytestrings when using the OverloadedStrings extension: import Data.ByteString.Char8 ()

import Data.ByteString.Lazy.Char8

...

f :: ByteString -> Bool

f "abc" = True

f _ = False

...

main = do

print $ f $ fromChunks ["abc"]

print $ f $ fromChunks ["a","bc"]

When I run the above, I get: True

True

Given that pattern matching is based on data constructors, how is it possible that (Chunk "abc Empty) and (Chunk "a" (Chunk "bc" Empty)) match the same pattern? Tom