[Jscheme-user] A probably elementary scheme question

[Borislav I. <bor...@ko...>]

Hi all,

In a program, I'm trying to construct and store an expression for later
evaluation. Consider:

(define l (LinkedList.))
(define point (java.awt.Point. 50 50))
(.add l point)
(define expr `(.remove l ,point))

Then:

(eval expr) 

properly removes the point from the linked list. This is fine. But after
replacing the point with a pair:

(define l (LinkedList.))
(define line (cons (java.awt.Point. 100 100) (java.awt.Point. 10 10))) 
(.add l line)
(define expr `(.remove l ,line))

Trying to evaluate the expression produces an error:

(eval expr)
=> SchemeException: expected object of type list (i.e. pair or empty),
but got: , "java.awt.Point[x=10,y=10]"

Why and what to do?

Thanks a lot in advance,
Boris