[racket] How to make eval work on define?

From: Matthias Felleisen (matthias at ccs.neu.edu)
Date: Sat Nov 17 08:34:25 EST 2012

Does this help: 

> #lang racket
> (define-namespace-anchor top)
> (parameterize ((current-namespace (namespace-anchor->namespace top)))
>   (eval '(define x 10))
>   (namespace-variable-value 'x))

eval takes a namespace and you need to supply it explicitly (as an argument) or implicitly (via a parameter setting). 

On Nov 17, 2012, at 1:06 AM, Monica Tomson wrote:

> Hi,
> When I use eval on an S-Expression, where there are something like (define len (...)), racket screams at me define: not allowed in an expression context in: (define len (make-length 10))
> My questions are:
> How to make eval work on definition?
> If eval is not designed to work on definitions, then is there some workarounds that can make it work?
> I appreciate any help!
> Thanks,
> Monica
> ____________________
>  Racket Users list:
>  http://lists.racket-lang.org/users

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