Is Excel the most used -- and fucntional -- programming lanuage on Earth?

[braver]

Heard that statement recently -- that Excel is a functional
programming language, and the most used one -- of any programming
languages -- on Earth!  Is it true?  Are there good examples of
typical FP style in Excel?

Cheers,
Alexy
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[Neil Mitchell]

Hi Alexy,

> Heard that statement recently -- that Excel is a functional
> programming language, and the most used one -- of any programming
> languages -- on Earth!  Is it true?  Are there good examples of
> typical FP style in Excel?

You can't define functions in Excel, hence its not really a functional
language. I'd go as far as saying its an expression-based programming
language, but that's it. It also has mutable state (if you use
circular references) so its not pure.

That said, the quote almost certainly comes from this paper (in the
title): http://research.microsoft.com/~simonpj/Papers/excel/index.htm

Thanks

Neil
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[Lennart Augustsson]

Excel is what I like to call a 0:th order functional language,
i.e., you can't even define functions, just values.  :)

        -- Lennart

On Jan 30, 2007, at 21:58 , Neil Mitchell wrote:

> Hi Alexy,
>
>> Heard that statement recently -- that Excel is a functional
>> programming language, and the most used one -- of any programming
>> languages -- on Earth!  Is it true?  Are there good examples of
>> typical FP style in Excel?
>
> You can't define functions in Excel, hence its not really a functional
> language. I'd go as far as saying its an expression-based programming
> language, but that's it. It also has mutable state (if you use
> circular references) so its not pure.
>
> That said, the quote almost certainly comes from this paper (in the
> title): http://research.microsoft.com/~simonpj/Papers/excel/index.htm
>
> Thanks
>
> Neil
> _______________________________________________
> Haskell-Cafe mailing list
> Haskell-Cafe@...
> http://www.haskell.org/mailman/listinfo/haskell-cafe

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[Dan Piponi-2]

On 1/30/07, Lennart Augustsson <lennart@...> wrote:
> Excel is what I like to call a 0:th order functional language,
> i.e., you can't even define functions, just values.  :)

Every cell with an expression in Excel is a function. The problem is
that the domains and codomains of these functions don't usually
contain functions. Maybe that makes it a first order functional
language.

But...suppose we had a spreadsheet a little like Haskell where each
cell has a static type, and the values can be Haskell functions. What
interesting things could we do with it that we couldn't do with Excel?
--
Dan
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[Jacques Carette]

There is a Maple plug-in for Excel.  If you have Maple (on Windows),
just start Excel and you'll see extra buttons.

This allows you to have cells containing symbols, as well as access to
all of Maple's functions.  This easily gets you a (very impure!)
higher-order functional language inter-operating very closely with Excel.

Jacques
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[Chris Eidhof]

The cool thing about Excel is that it's like Function Reactive  
Programming. When you update the value of a cell, all the other cells  
that reference to it get updated too. That's pretty cool to have in  
GUI's as well, and Haskell has that too. See [1].

-chris

[1]: http://www.haskell.org/frp/

On 30 Jan, 2007, at 22:46 , Alexy Khrabrov wrote:

> Heard that statement recently -- that Excel is a functional
> programming language, and the most used one -- of any programming
> languages -- on Earth!  Is it true?  Are there good examples of
> typical FP style in Excel?
>
> Cheers,
> Alexy
> _______________________________________________
> Haskell-Cafe mailing list
> Haskell-Cafe@...
> http://www.haskell.org/mailman/listinfo/haskell-cafe

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[Magnus Therning]

On Tue, Jan 30, 2007 at 22:20:14 +0000, Lennart Augustsson wrote:
>Excel is what I like to call a 0:th order functional language,
>i.e., you can't even define functions, just values.  :)

Ah, that would explain why the presentation from Credit Suisse at
CUFP[1] has that expression in it :-)

/M

[1]: http://www.galois.com/cufp/

--
Magnus Therning                             (OpenPGP: 0xAB4DFBA4)
magnus@...             Jabber: magnus.therning@...
http://therning.org/magnus


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[Lennart Augustsson]

I think you're using a somewhat non-standard definition of function.
Say that I have the Haskell expression
   let x = 5
       y = x + 2
       z = x * y
   ...
Would you call y and z functions?  I wouldn't, I would call them
definitions with free variables in the rhs.

But that's beside the point.  When you ask what you could do with
functions in Excel do you mean from a practical or theoretical
perspective?
 From a practical perspective I'd say the difference is immense.
In Excel today, if you want to do, e.g., a map you do it by copying
a formula.  So any change in that formula needs N changes in the
spreadsheet.  With functions, you could do the change in one place.
Furthermore, if you add some kind of lists/arrays (which Excel sort
of has), you can express things in a much easier way.
At work we have added a way to define functions in Excel.  It's quite
clunky since you have to shoehorn it into Excel, but even so it's been
quite popular and change the way people use Excel.

 From a theoretical perspective, it would increase the class of problems
expressible in Excel.  I'm not sure if these complexity classes have any
names, though.  Assuming unit time for the basic Excel functions (+,  
-, etc),
today you can only express formulas that take at most linear time, in  
the
size of the formula, to calculate.  With functions, this would  
increase to
at least exponential (at least that's my gut reaction).

        -- Lennart

On Jan 30, 2007, at 23:59 , Dan Piponi wrote:

> On 1/30/07, Lennart Augustsson <lennart@...> wrote:
>> Excel is what I like to call a 0:th order functional language,
>> i.e., you can't even define functions, just values.  :)
>
> Every cell with an expression in Excel is a function. The problem is
> that the domains and codomains of these functions don't usually
> contain functions. Maybe that makes it a first order functional
> language.
>
> But...suppose we had a spreadsheet a little like Haskell where each
> cell has a static type, and the values can be Haskell functions. What
> interesting things could we do with it that we couldn't do with Excel?
> --
> Dan

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[Bulat Ziganshin-2]

Hello Alexy,

Wednesday, January 31, 2007, 12:46:33 AM, you wrote:

> Heard that statement recently -- that Excel is a functional
> programming language, and the most used one -- of any programming
> languages -- on Earth!  Is it true?

that's true and breaks any words that FP thinking is "unnatural" for
peoples :)

what matters here is that in Excel you *don't* define calculation
order which makes it a functional rather than imperative approach to
computations

--
Best regards,
 Bulat                            mailto:Bulat.Ziganshin@...

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[Bjorn Lisper]

>Dan Piponi:
>On 1/30/07, Lennart Augustsson <lennart@...> wrote:
>> Excel is what I like to call a 0:th order functional language,
>> i.e., you can't even define functions, just values.  :)
>
>Every cell with an expression in Excel is a function. The problem is
>that the domains and codomains of these functions don't usually
>contain functions. Maybe that makes it a first order functional
>language.

Or maybe not. Yes, every cell in isolation contains an expression possibly
with free variables, and so can be seen as a function in those
variables. But these variables are not unbound since they are defined
elsewhere in the spreadsheet. Thus, the sheet is rather a system of
equations defining values, not functions. I think 0:th order is a good term
:-)

>But...suppose we had a spreadsheet a little like Haskell where each
>cell has a static type, and the values can be Haskell functions. What
>interesting things could we do with it that we couldn't do with Excel?

I had a MSc student doing something in this direction some years ago. He
made a Haskell interface which was intended to work like a spreadsheet. In
this interface, every declaration has a value window (if the entity declared
has a showable type) and a declaration window. A designated button triggers
a recompilation, and thus also a recalculation of all declared values -
this, I think, captures the essence of spreadsheets which is to be able to
make changes and quickly see the results. In order to support the kind of
array omputations often done in spreadsheets, an extended array module was
defined which declares a number of array functions and other conveniences.

See http://www.mrtc.mdh.se/index.php?choice=projects&id=0041.

Björn Lisper
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[Dan Piponi-2]

On 1/31/07, Lennart Augustsson <lennart@...> wrote:
> I think you're using a somewhat non-standard definition of function.
>    let x = 5
>        y = x + 2
>        z = x * y
>    ...
> Would you call y and z functions?

Ah...we don't disagree on what a function is, I'm just parsing
spreadsheets differently from you. I was imagining a spreadhseet along
the lines of http://sigfpe.blogspot.com/2006/11/from-l-theorem-to-spreadsheet.html
where every cell is a function of the entire spreadsheet.
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[Fritz Ruehr]

I think Pivotal (<http://www.cs.kent.ac.uk/projects/pivotal/>) has the "live update" behavior of spreadsheets.

I haven't played with it yet, but I saw Keith Hanna show off his earlier Vital system; it even updates "backwards" in some sense; see the "Direct manipulation" section at his site (<http://www.cs.kent.ac.uk/projects/pivotal/adt-manip.html>). 

Finally, it also does some nice things with graphics, a la Conal's Pan (and now Eros), probably could do Jerzy/Clastic-type stuff, too.

  --  Fritz

On Jan 31, 2007, at 4:06 AM, Bjorn Lisper wrote:

But...suppose we had a spreadsheet a little like Haskell where each

cell has a static type, and the values can be Haskell functions. What

interesting things could we do with it that we couldn't do with Excel?

I had a MSc student doing something in this direction some years ago. He

made a Haskell interface which was intended to work like a spreadsheet. In

this interface, every declaration has a value window (if the entity declared

has a showable type) and a declaration window. A designated button triggers

a recompilation, and thus also a recalculation of all declared values -

this, I think, captures the essence of spreadsheets which is to be able to

make changes and quickly see the results. In order to support the kind of

array omputations often done in spreadsheets, an extended array module was

defined which declares a number of array functions and other conveniences.

See http://www.mrtc.mdh.se/index.php?choice=projects&id=0041.

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