In " returnIO x = IO $ \ s -> (# s, x #)" what are the # symbols?


That's special syntax to make an unboxed tuple. See the manual section on
unboxed types[1].
[1]:
https://downloads.haskell.org/~ghc/7.6.3/docs/html/users_guide/primitives.ht...
On Mon, Jul 13, 2015 at 5:23 PM, Jeffrey Brown
That appears here: http://hackage.haskell.org/package/base-4.8.0.0/docs/src/GHC-Base.html#line-...
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You may also like this Wiki page about state tokens[1] (note: I'm the
author).
[1] https://wiki.haskell.org/Evaluation_order_and_state_tokens
On Mon, Jul 13, 2015 at 5:25 PM Tikhon Jelvis
That's special syntax to make an unboxed tuple. See the manual section on unboxed types[1].
[1]: https://downloads.haskell.org/~ghc/7.6.3/docs/html/users_guide/primitives.ht...
On Mon, Jul 13, 2015 at 5:23 PM, Jeffrey Brown
wrote: That appears here: http://hackage.haskell.org/package/base-4.8.0.0/docs/src/GHC-Base.html#line-...
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participants (3)
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Jeffrey Brown
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Michael Snoyman
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Tikhon Jelvis