A question about run-time errors when class members are undefined

[Anthony Clayden]

On Fri, 5 Oct 2018 at 9:00 PM, Jurriaan Hage <J.Hage at uu.nl> wrote:

>
> We first go the slavish route, to provide a basis for changing things
> later.


Ah. That comment seemed strange, but I've just read up on Helium: you're
aiming to provide a beginners' environment for Haskell.

Then without type classes, I'm wondering what Helium is doing now for
arithmetic or equality-testing or show or read? Do you mean you've somehow
'faked' the Prelude classes, but don't yet allow programmers to declare
their own classes/instances?

Being able to declare your own datatypes without writing instances for them
seems particularly awkward.

If Helium essentially supports less than H98, I'm wondering why you didn't
start with Hugs, and work on it giving better error messages? I'm finding
Hugs very easy to hack; the messages are particularly easy to work with.
(OK it's written in C++, but the 'interesting' parts are just function
calls, so the host language seems irrelevant.)


AntC
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