Re: [Haskell-cafe] Is Excel the most used -- and fucntional -- programming lanuage on Earth?

Dan Piponi: On 1/30/07, Lennart Augustsson wrote:

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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