Tomasz Zielonka wrote:
On Fri, Apr 23, 2004 at 03:32:54AM +0200, Sebastian Sylvan wrote:
First you need to parse the expression into a Haskell data type. For this I would recommend Parsec (see Haskell.org). The Haskell data type would be something like
data Expr = AtomD Double | AtomI Integer | Add Expr Expr | Mul Expr Expr | Sub Expr Expr | ....
There is no need to introduce a datatype - for one parameter functions you can parse text directly to a (Double -> Double) function. Of course if you want to do more things with your functions than just evaluation (like printing, symbolic differentiation), introducing a datatype is a good idea.
The original poster used the term "equation" which to me indicated that he might have things like unknown variables in stuff. In other words: He would have to do some form of manipulation of the expression in order to get the result.
/S
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