I have had this idea for a program for ages, but I don't think I'm ever going to be able to make it.

The idea started out as a spreadsheet app, but where the formulas are based on haskell/lambda calculus - crucially:
* the syntax is much nicer than excel's standard.
* first class functions abound - you can pass functions to other functions. You can put a function in a cell without applying it, and then later use that function against values elsewhere.

I then extended the idea further to like... a programmable data soup.

So instead of it being functions embedded in a spreadsheet, it's a programming environment where spreadsheets are embedded inside it