Proposal: Export Any from Unsafe.Coerce

Simon Peyton Jones simonpj at
Tue Sep 15 21:41:23 UTC 2015

Certainly OK with me too.  GHC.Exts is the right place.


From: Libraries [mailto:libraries-bounces at] On Behalf Of Richard Eisenberg
Sent: 15 September 2015 15:10
To: David Feuer
Cc: Haskell Libraries
Subject: Re: Proposal: Export Any from Unsafe.Coerce

Sounds reasonable to me. Also, see #10886, which this request prompted me to make.


On Sep 14, 2015, at 1:44 PM, David Feuer <david.feuer at<mailto:david.feuer at>> wrote:

Any is the sanctioned intermediary for unsafeCoerce. GHC claims to guarantee that any lifted type can be coerced to and from Any without harm. Yet Any seems to be available only from the deeply mystical GHC.Prim, which users outside the GHC source tree are never supposed to import. While GHC.Exts would be an acceptable place, I think Unsafe.Coerce is more appropriate, and will make it easier for users to find this type.
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