#### Re: Haskell: questions

Tried to define new type with Show. It any. How to understand error status code?

Really I should bypass over 9000 syntactic forms to select one is unique

The correct?`newtype Vector = Double Double Double deriving (Show, Eq)`

`Prelude>:l card.hs [1 of 1] Compiling Main (card.hs, interpreted) card.hs:27:18: error: * The constructor of a newtype must have exactly one field but ` Double ' has two * In the definition of data constructor ` Double' In the newtype declaration for ` Vector' | 27 | newtype Vector = Double Double Double deriving (Show, Eq) | ^^^^^^^^^^^^^^^^^^^^`

You like simply vector arranged. And there show it is already implemented.

And so that, you newtype incorrectly wrote down. I above gave.