Re: How to include a file/definition temporarily?

[David Kastrup]

Carl Sorensen <address@hidden> writes:

> On 9/20/10 3:54 AM, "David Kastrup" <address@hidden> wrote:
>
>> Carl Sorensen <address@hidden> writes:
>> 
>>> This is a good thought as a temporary workaround.  However, it won't work
>>> as-is, because fretboard-table is a hash table.  We'd need to define a
>>> hash-table copy function:
>>> 
>>> (define (hash-table-copy my-table)
>>>   (let ((new-hash-table (make-hash-table 100)))
>>>     (hash-for-each (lambda (key value)
>>>                      (hash-set! new-hash-table key value))
>>>                    my-table)
>>>      new-hash-table))
>>     (hash-fold
>>       (lambda (key value tab)
>>         (hash-set! tab key value))
>>       (make-hash-table 101)
>>       my-table))
>> 
>> Does not require a closure.  And the size argument is recommended to be
>> prime.  Which 100 is not exactly.
>
> Thanks.  I looked at hash-fold, and thought about how it could work,
> but the description in the Guile docs (which was a bit cryptic) didn't
> help me find this solution.

To make it a solution, it is missing the return value from the fold
function.  Sigh.  So make that

     (hash-fold
       (lambda (key value tab)
         (hash-set! tab key value)
         tab)
       (make-hash-table 101)
       my-table))

Presumably hash-for-each is implemented via hash-fold (as the latter is
the only mentioned in the guile documentation), so this version is
conceivably faster.  More importantly, one can find it in the guile
documentation.

-- 
David Kastrup