[Haskell-cafe] Moggi :: CT - Hask

2009-02-07 Thread Gregg Reynolds
Hi,

I had a monadic revelation at about 3 am.  The answer to the question
what is an IO value, really? is who cares?  I just posted a blog
entry discussing how CT found it's way from Moggi into Haskell at
http://syntax.wikidot.com/blog (hence the title; Moggi as functor).
It addresses the question of what such things are and why Moggi's
insight is so brilliant.  Feedback welcome, but please remember this
is coming from a non-mathematician who likes to write.  If you find
anything there that outrages your inner Russell, please correct me,
but be gentle.

Thanks,

gregg
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Re: [Haskell-cafe] Moggi :: CT - Hask

2009-02-07 Thread Dan Doel
On Saturday 07 February 2009 12:11:29 pm Gregg Reynolds wrote:
 I had a monadic revelation at about 3 am.  The answer to the question
 what is an IO value, really? is who cares?  I just posted a blog
 entry discussing how CT found it's way from Moggi into Haskell at
 http://syntax.wikidot.com/blog (hence the title; Moggi as functor).
 It addresses the question of what such things are and why Moggi's
 insight is so brilliant.  Feedback welcome, but please remember this
 is coming from a non-mathematician who likes to write.  If you find
 anything there that outrages your inner Russell, please correct me,
 but be gentle.

As far as I know, Moggi didn't really have anything directly to do with 
Haskell. He pioneered the idea of monads being useful in denotational 
semantics. But it was Wadler that recognized that they'd be useful for 
actually writing functional programs (see his The Essence of Functional 
Programming). So one might say that it was his doing that brought monads to 
Haskell proper.

-- Dan
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Re: [Haskell-cafe] Moggi :: CT - Hask

2009-02-07 Thread Gregg Reynolds
Hi Dan,

On Sat, Feb 7, 2009 at 12:00 PM, Dan Doel dan.d...@gmail.com wrote:

 On Saturday 07 February 2009 12:11:29 pm Gregg Reynolds wrote:

 As far as I know, Moggi didn't really have anything directly to do with
 Haskell. He pioneered the idea of monads being useful in denotational
 semantics. But it was Wadler that recognized that they'd be useful for
 actually writing functional programs (see his The Essence of Functional
 Programming). So one might say that it was his doing that brought monads
 to
 Haskell proper.


From what I've read Wadler was clearly the guy who thought of using monads
in Haskell, but he explicitly credits Moggi for coming up with the general
idea.  Moggi just as clearly knew he was on to something powerful and useful
(e.g. something  that could lead to the introduction of higher order
modules in programming languages like ADA or ML).  What I would be
interested in knowing is whether it was Wadler or Moggi who first realized
monads (and CT) could be encoded directly in a target language, not just in
a semantic metalanguage.  Plus there were other people working in the same
area; I just don't know the detailed history.  Might be a good subject for a
blog post for somebody who does.

FYI I made a few corrections to my original post.

-gregg
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