Typesafe MRef with a regular monad

[Simon Peyton-Jones]

You can't overwrite an entry with a value of a different type, because
the keys are typed!  Any more than you can overwrite an IORef with a
value of a different type.
S

| -----Original Message-----
| From: Ralf Hinze [mailto:ralf@informatik.uni-bonn.de]
| Sent: 06 June 2003 15:01
| To: Simon Peyton-Jones; Tim Sweeney; haskell@haskell.org; Ashley
Yakeley
| Subject: Re: Typesafe MRef with a regular monad
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| Am Freitag, 6. Juni 2003 15:47 schrieb Simon Peyton-Jones:
| > Yes, one *could* use dynamic types.  But the check would always
succeed!
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| Why is that? If I overwrite an entry with a value of a different type,
| then the check fails. I am certainly missing something ...
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| Cheers, Ralf
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