Re: [Haskell-cafe] OOP'er with (hopefully) trivial questions.....

On Dec 17, 2007 10:47 PM, Nicholls, Mark wrote:

"The constructor of a newtype must have exactly one field but `R' has two In the newtype declaration for `Rectangle'"

It doesn't like

"newtype Rectangle = R Int Int"

A newtype can only have one constructor, with one argument, and is essentially a wrapper for that argument type. In the general case, you want to use "data" instead of "newtype": data Rectangle = R Int Int Stuart