[Haskell-cafe] A different Maybe maybe
mail at joachim-breitner.de
Wed Mar 7 17:32:08 EST 2007
[Also on http://www.joachim-breitner.de/blog/archives/229-A-different-Maybe-maybe.html]
For a while I have been thinking: Isn’t there a way to get rid of the
intermediate Maybe construct in a common expression like “fromMaybe
default . lookup”. It seems that a way to do that would be to pass more
information to the Maybe-generating function: What to do with a
Just-Value, and what to return in case of Nothing. This leads to a new
definion of the Maybe data type as a function. Later I discovered that
this seems to work for any algebraic data type.
This is probably nothing new, but was offline at the time of writing, so
I didn’t check. This means that this might also be total rubbish. Enjoy.
* “Algebraic Data Type Done Differently” (PDF-File) at
* “Algebraic Data Type Done Differently” (Literate Haskell Source)
Comments are appreciated.
Greetings from my holidays,
Joachim "nomeata" Breitner
mail: mail at joachim-breitner.de | ICQ# 74513189 | GPG-Key: 4743206C
JID: joachimbreitner at amessage.de | http://www.joachim-breitner.de/
Debian Developer: nomeata at debian.org
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