Re: [Haskell-cafe] Re: Maybe to Either -- is there a better way?

On 03/08/2010, at 10:09 PM, Ertugrul Soeylemez wrote:

Tom Davies wrote:

...

I find it convenient sometimes to convert a Maybe value to an Either thus (excuse the syntax, it's CAL, not Haskell):

maybeToEither :: a -> Maybe b -> Either a b; maybeToEither errorValue = maybe (Left errorValue) (\x -> Right x);

As a side note, this is perfectly valid Haskell code, even though it's quite verbose. The equivalent:

maybeToEither :: a -> Maybe b -> Either a b maybeToEither leftValue = maybe (Left leftValue) Right

I like that better, and CAL supports that, thanks.

Honestly I find this better than the completely points-free variants posted in the other subthread. They demonstrate overusing points-free style.

I agree -- as an inexperienced functional programmer, but not a complete beginner, I found the points free versions incomprehensible! Tom