Re: How lazy is DData.Seq?

Am Samstag, 8. Mai 2004 18:37 schrieben Sie:

--- Wolfgang Jeltsch wrote:

...

Hello,

I would suspect that in DData.Seq the result of head (singleton 'a' `append` undefined) is 'a' but instead it is _|_. Why is this the case?

I have the invariant that sublists are not empty. There is, for example:

append as None = as

Is this necessary/desirable? I have an application where I think that it can be important for efficiency that the above expression evaluates to 'a'. So I would like it to not result in _|_.

Cheers, JP.

Wolfgang