This and the fact that you may leave record fields unspecified when initially constructing a record are two things I'd probably change if I could. In the rare case of a class with a method that will usually be an error, you could still define that as the default method implementation in the class. 

On Mon, Oct 1, 2018, 04:36 Jurriaan Hage, <J.Hage@uu.nl> wrote:
Hello,

We are adding classes and instances to Helium.

We wondered about the aspect that it is allowed to have a class instance
of which not all fields have a piece of code/value associated with them, and
that as a result when you happen to call these, a run-time error results.
 (see Sec. 4.3.2 of the Haskell 2010 report).

Does anyone know of a rationale for this choice, since it seems rather unhaskell-like.

best,
Jur

_______________________________________________
Haskell-prime mailing list
Haskell-prime@haskell.org
http://mail.haskell.org/cgi-bin/mailman/listinfo/haskell-prime