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Re: Problems with field initialization: Proposal

This page is part of the web mail archives of SRFI 76 from before July 7th, 2015. The new archives for SRFI 76 contain all messages, not just those from before July 7th, 2015.

Andre van Tonder <andre@xxxxxxxxxxxxxxxxxxx> writes:

>  As an example, the hash-table example could be expressed:
>   (define-type hash-table
>     (constructor (k) (lambda (pred hasher size)
>                        (k pred
>                           hasher
>                           (make-vector (nearest-prime size))
>                           0)))         
>     (fields (pred   immutable)
>             (hasher immutable)
>             (data   mutable)
>             (count  mutable))))
>   (define-type eq-hash-table
>     (parent hash-table)
>     (constructor (k) (lambda (pred hasher size)
>                        (k pred
>                           hasher
>                           size
>                           0)))
>     (fields (gc-count mutable)))

Thanks for writing this up---this helps imagining what it'd look like.

I'm confused about the K argument in the EQ-HASH-TABLE example.  Does
it call the primitive constructor of the underlying record type, or
the construction procedure of the supertype?  If the former, there's
one argument missing.  (And I'd ask how I could reuse the construction
procedure of the supertype.)  If the latter, what's it's return value,
and how do I transform it into an instance of the subtype?

Cheers =8-} Mike
Friede, Völkerverständigung und überhaupt blabla