[Haskell] help with some basic code that doesn't work

[Malcolm Wallace]

Matthew Walton <matthew at alledora.co.uk> writes:

> (==) works on types which are members of the Eq typeclass. You can 
> define this instance manually, or, since your type is nice and simple, 
                                     ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> you can get Haskell to derive it for you.

Just a comment, since a couple of people have made similar statements.
Haskell will derive Eq for arbitrarily complex types - there is no
restriction to "simple" types, whatever they might be.  It will
always give you the "obvious" structural equality.  There /are/
occasions when structural equality is not quite what you want, but
that decision is entirely orthogonal to whether the type definition
is simple or complex.

Regards,
    Malcolm