Re: [Haskell-cafe] Monads, do and strictness

On Sat, Jan 21, 2012 at 1:45 PM, David Barbour wrote:

On Sat, Jan 21, 2012 at 10:08 AM, Roman Cheplyaka wrote:

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* David Barbour [2012-01-21 10:01:00-0800]

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As noted, IO is not strict in the value x, only in the operation that generates x. However, should you desire strictness in a generic way, it would be trivial to model a transformer monad to provide it.

Again, that wouldn't be a monad transformer, strictly speaking, because "monads" it produces violate the left identity law.

It meets the left identity law in the same sense as the Eval monad from Control.Strategies.  http://hackage.haskell.org/packages/archive/parallel/3.1.0.1/doc/html/src/Co...

The Eval monad has the property: return undefined >>= const e = e.

From what I can tell, your proposed monads do not.

-- Dave Menendez http://www.eyrie.org/~zednenem/