Hi,
after thinking about it a bit, I think it might be necessary to provide
more context, so I opened an issue in my toy project this relates to:
https://github.com/formrre/soft-heap-haskell/issues/5
--
Timo
On Mon, Aug 21, 2017 at 5:52 AM, Timotej Tomandl
As the title says.
Motivation: in a mutable code I want to keep some parameters strictly immutable, i.e. not sharing s with the whole mutable type
I think this is best illustrated by 2 examples: 1. abstract example: imagine I have a type X a b c and another type Y a b and I want to prevent any case where the first parameter of X "a" is shared with it's third parameter "c" i.e. X a b (Y a a), X a b (Y a b), X a b (Y b a), X a b (Y a d) etc., any nestings in Y referencing a etc. but allow X a b (Y b b), X a b (Y b c) and any other combination not ruled out above 2. concrete example: imagine I have a type: Item s element key where s is used in the same way as in STRef s a, i.e. it cannot leak outside of a certain context, but I want the key to be immutable i.e. independent of s under any circumstences, so I can't write a type like: Item s element (STRef s refType) this is equivalent to disallowing X a b (Y a d) in 1.
Is there any way to write a restriction like this in Haskell?
-- Timo