Language complexity & beginners (Was: New type of ($) operator in GHC 8.0 is problematic)
eir at cis.upenn.edu
Sat Feb 6 15:17:36 UTC 2016
I have made a ticket #11549 (https://ghc.haskell.org/trac/ghc/ticket/11549) requesting a -fshow-runtime-rep flag (recalling that the name levity will soon be outdated) as described in this thread. I will make sure this gets in for the release of 8.0.
- You're quite right that (.) could be generalized. But I'll wait for someone to really want this.
- I don't have a non-contrived example of the use of ($) with unlifted types. It's quite possible that when adding the dirty runST hack, it was observed that an unlifted type would be OK. At that point, the type of ($) didn't need to become so elaborate. And now we're just trying not to change old (but perhaps unrequested) behavior.
- For the record, this debate is entirely unrelated to the runST impredicativity hack. (Except, as noted above, perhaps in history.) That hack remains, basically unchanged.
- On Feb 6, 2016, at 9:55 AM, Roman Cheplyaka <roma at ro-che.info> wrote:
> I would call this a simplification rather than a lie.
This is a very convincing argument.
- Thanks, also, for the voice of support. What I love about the Haskell community is that we can have an impassioned debate full of strong opinions, and it all very rarely devolves into a proper flame war. All the posts I've seen in this thread have been constructive and helpful. Thanks.
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