Mercurial > repos > other > SevenLanguagesInSevenWeeks
changeset 96:f548c8460d15
Add extra note about monadic-ness
| author | IBBoard <dev@ibboard.co.uk> |
|---|---|
| date | Sun, 30 Jun 2019 15:50:33 +0100 |
| parents | 83b4f23b9df8 |
| children | 85a5e9a6ef5c |
| files | 7-Haskell/day3.hs |
| diffstat | 1 files changed, 1 insertions(+), 0 deletions(-) [+] |
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--- a/7-Haskell/day3.hs Sun Jun 30 15:10:23 2019 +0100 +++ b/7-Haskell/day3.hs Sun Jun 30 15:50:33 2019 +0100 @@ -25,6 +25,7 @@ -- Note 2: The input value has to be a "Just x" otherwise we can "Couldn't match type 'Maybe' with []" -- Note 3: I can't get anything out of this other than "Just <val>", even if I include ">>= return" -- Example usage: Just hashtable >>= ht_lookup "Phonetic" >>= ht_lookup "Greek" >>= ht_lookup "alpha" + -- This is monadic because "Just hashtable >>= ht_lookup "Phonetic" >>= ht_lookup "foo" >>= ht_lookup "alpha" >>= return" doesn't explode but returns Nothing ht_lookup :: String -> [(String, a)] -> Maybe a ht_lookup _ [] = Nothing ht_lookup search_key ((key, value):tail)