On 2008 Nov 12, at 5:38, Alberto G. Corona wrote:
Is there any abstract container  that permits the addition of  new types of data? I know how to simulate the extension of Algebraic datatypes, but this does not permit the addition of data with new types in the same container and recover them in a  type-safe way.

Did I reinvent the Weel? I found something, that permits this for any Typeable datatype. For example

I think you want http://www.haskell.org/ghc/docs/latest/html/libraries/base/Data-Dynamic.html .

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brandon s. allbery [solaris,freebsd,perl,pugs,haskell] allbery@kf8nh.com
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electrical and computer engineering, carnegie mellon university    KF8NH