Looks like unbound? and symbol-value take quoted symbols if passing them
directly: And for list you have to use the transformed name scheme#list
#;2> (unbound? 'x)
#t
#;3> (define x 1)
#;4> (unbound? 'x)
#f
#;5> (symbol-value 'x)
1
#;6> (symbol-value 'scheme#list)
#
On Thu, Jun 22, 2023 at 10:15 PM Pan Xie wrote:
> Hello
>
> I am new to CHICKEN scheme and here is a (very) quick question of how to
> check whether a symbol is bound.
>
> I know it doable but I can't find the way.
>
> I don't find the methods from the main CHICKEN manual document. Then I
> import the "symbol-value-utils" module. I believe the "unbound?" or
> "symbol-value" will do what I want, but to my surprise they does NOT:
>
> I expect `symbol-value' will give me value of a symbol, but it will
> throw exception for an
> undefined symbol, even I provide the default value:
>
> (symbol-value foo #f)
> Error: unbound variable: foo
>
> I expect (symbol-value (string->symbol "list")) will give me the list
> procedure, but what I get is '#f'
>
> (symbol-value (string->symbol "list"))
> #f
>
> I expect (unbound? foo) will return True value, but it just throw
> exception.
>
> Does CHICKEN scheme provide facilities that make user check whether
> arbitrary symbol is bound or get its value, just like the `boundp' or
> `symbol-value' in Common Lisp?
>
> Thanks
> Pan
>
>
>
