[Haskell-cafe] Infinite types should be optionally allowed

Job Vranish jvranish at gmail.com
Mon Feb 21 16:23:02 CET 2011

On Sun, Feb 20, 2011 at 8:56 PM, Brandon Moore <brandon_m_moore at yahoo.com>wrote:
> Typechecking with regular types isn't hard.

So do I have the right idea then? To check against a signature, I can just
unify the two types and then check if the unified type is 'equivalent' (is
there a special word for this kind of equivalence?) to the original
I've gotten the impression from multiple people that type checking with
infinite types is hard. Maybe this isn't so?

> The problem is, the type system
> is almost useless for catching bad programs. Every closed lambda expression
> is typeable if infinite types are allowed.

Yes, this part I understand quite well :)

Usually systems add some sort of

ad-hoc restriction on regular types, like requiring that all all cycles
> pas through

a record type.

Yeah, what I really want is just a better ad-hoc restriction or annotation.
I quite routinely work with code that would be much more simple and elegant
with infinite types.

- Job
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