Kalkar

It will be a general purpose text based calculator/calculator component written in Delphi.

Users can define variables and functions. Functions can be defined in 2 ways:

with a minimal functional language (inspired by Haskell) built in Kalkar. Examples:

fact n = if n == 0 then 1 else fact (n-1)
sum List = if empty List then 0 else head List + sum Tail List
SomeList = 1,2,3
sum (SomeList, 4, 5) - (2^2)

last line would print 11

with any external programming language which is able to read input (arguments) from command-line and to print answer on stdout. If user uses some function not defined in Kalkar, then Kalkar looks for a script with same name from a designated folder, runs it with arguments and reads output.

Something is already done -- simple expressions and defining variables and lists and exernal functions. And there is an user interface for it.

Missing:

implementation of functional language. Grammar is ready.
configuration part -- what program to use for executing different scripts.
better user interface -- main problem with current ui is that one can get previous expression back with down arrow and this is unnatural for people used with terminals.

Grammar

Input       -> List
List        -> Sum [, List]
Sum         -> Term {('+'|'-') Term}
Term        -> Factor {('*'|'/') Factor}
Factor      -> SignedStuff ['^' Factor]
SignedStuff -> {('-'|'/')} Stuff
Stuff       -> ( posnum | Ident | '(' [List] ')' )
Ident       -> name [Stuff | '=' List]

'/' on the line of SignedStuff is unary division operator: '/2' means '1/2'. It's good for constructing root operator '^/' so you can write '4^/2' instead of '4^(1/2)'

Variables holding lists and functions returning lists must begin with uppercase letter.

Download current work from download page
Code is also available from Subversion repository (info here)

My name is Aivar Annamaa and email is [aivarannamaa (server is hotmail)]