On 2019-11-08 7:12 pm, Freeman Gilmore wrote:
\version "2.19.83"
#((define h (make-hash-table 114))
(display h)
(hashq-set! h 3 "val3")
(display (hashq-ref h 3)))
Wrong type to apply: #<unspecified>
Could someone explain why I get this error?
"(define h (make-hash-table 114))" returns (or evaluates to)
#<unspecified> which is not a procedure. (#<unspecified> is a special
value in Scheme, which you can test for with the "unspecified?"
predicate.)
It helps to remember that "(proc 1 2 3)" is shorthand for "(apply proc
'(1 2 3))". Your original expression, therefore, is functionally
equivalent to this:
;;;;
(apply (define h (make-hash-table 114))
(list (display h)
(hashq-set! h 3 "val3")
(display (hashq-ref h 3))))
;;;;
The solution is to use "begin":
%%%%
\version "2.19.83"
#(begin
(define h (make-hash-table 114))
(display h)
(hashq-set! h 3 "val3")
(display (hashq-ref h 3)))
%%%%
-- Aaron Hill
