_ just means "ignore this parameter, I'm not going to use it"

On Tuesday, November 11, 2014, Roelof Wobben <r.wobben@home.nl> wrote:
Thanks, this is working well.

But just for understanding

in the part acc x Nothing   x is the input string,
and in the part _j means the same as (xs:x)

Roelof
 


Alex Hammel schreef op 10-11-2014 22:47:
It's an indentation issue. Make sure that there are no spaces before the bit about 'last5 = foldr acc' etc.

On Mon, Nov 10, 2014 at 12:48 PM, Roelof Wobben <r.wobben@home.nl> wrote:
Roelof Wobben schreef op 10-11-2014 20:59:
last5 :: [a] -> Maybe a
   last5 = foldr acc Nothing where
       acc x Nothing  = Just x
       acc _ j        = j

When I enter this in GHCI  I see this error :

Illegal type signature: ‘[a] -> Maybe a last5’




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