Hi Mark!
Thank you, that is the solution and the explanation!
I read my procedures multiple times, wondering whether I am returning
another hash table or anything. It would have taken me a long time
before trying to create the vector without the additional quotes.
Regards,
Zelphir
On 11/24/19 9:04 AM, Mark H Weaver wrote:
> Hi Zelphir,
>
> Zelphir Kaltstahl <zelphirkaltst...@posteo.de> writes:
>
>> I've noticed a strange behavior of hash tables. I put in symbols as keys
>> and integers as values, but when I try to get the integers out again by
>> using the same symbol, I get back a #f instead. Here is the code I am using:
>>
>> ~~~~~~~~
>> (use-modules
>> ;; SRFI 60: procedures for treating integers as bits
>> (srfi srfi-60)
>> (ice-9 hash-table))
>>
>>
>> (define SQUARES
>> ;; vector, constant time access
>> #('A1 'B1 'C1 'D1 'E1 'F1 'G1 'H1
>> 'A2 'B2 'C2 'D2 'E2 'F2 'G2 'H2
>> 'A3 'B3 'C3 'D3 'E3 'F3 'G3 'H3
>> 'A4 'B4 'C4 'D4 'E4 'F4 'G4 'H4
>> 'A5 'B5 'C5 'D5 'E5 'F5 'G5 'H5
>> 'A6 'B6 'C6 'D6 'E6 'F6 'G6 'H6
>> 'A7 'B7 'C7 'D7 'E7 'F7 'G7 'H7
>> 'A8 'B8 'C8 'D8 'E8 'F8 'G8 'H8))
> I guess that you meant for this to be a vector of symbols. In fact, it
> is a vector of lists of the form (quote <symbol>), for which '<symbol>
> is a shorthand.
>
> scheme@(guile-user)> (vector-ref SQUARES 0)
> $10 = (quote A1)
>
> To fix the problem, remove all of the apostrophes (') from the elements
> of the vector literal above. Like list literals, vector literals take
> raw values, not expressions.
>
>> (hash-ref SQUARES-TO-INTEGERS 'A1)
> scheme@(guile-user)> (hash-ref SQUARES-TO-INTEGERS 'A1)
> $11 = #f
> scheme@(guile-user)> (hash-ref SQUARES-TO-INTEGERS ''A1)
> $12 = 1
>
> Mark
