[Haskell] IO == ST RealWorld

Simon Peyton-Jones simonpj at microsoft.com
Tue Jan 24 04:17:20 EST 2006

| Is there any reason why IO should not be defined as:
|   > type IO a = ST RealWorld a
| in implementations that support ST?
| This way IORef/STRef and IOArray/STArray can be merged. I know under
| hood they already share code, but this way they can also share an

Indeed, this was the way we had it originally in GHC.  It does seem like
a good idea.  We changed it for reasons that I know that we have
forgotten, alas, because we tried to recall about a year ago.   It's
always possible that the original reasons for the change no longer

Perhaps someone can try it out?


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