[Haskell-cafe] There is no null; Maybe/Option types

[Christopher Done]

On 22 April 2011 21:26, Henning Thielemann <lemming at henning-thielemann.de>wrote:

>  In idiomatic Haskell you would write
>
> case userList of
>   Nothing -> Nothing
>   Just plainUserList =
>      let user = findUser "bob" plainUserList
>      ...
>
> since (userList /= Nothing) requires an Eq instance without need and it
> requires fromJust. Or was there an educational purpose to write it with (/=
> Nothing) ?
>

Educational; it was just to make it look like and have similar meaning (as I
perceived it) to the Fantom code. (I'd never write code like this; I use
case analysis and avoid if.)
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