What's wrong with `match`? It seems to be what you want. Macro is not going to help you here.
On Mon, Jul 6, 2020 at 3:47 AM Oualmakran Yassine <[email protected]> wrote: > Hello, > > I have some difficulties when trying to create a macro doing some pattern > matching on a hash-table and was hoping finding some help. > The macro is taking a hash-table as parameter and I would like to extract > the value for the key 'name. > I did several trials of my macro with what should be, for my > understanding, the same hash-table but got always a different result. > Suprisingly, when I'm trying the same partern matching in a simple "match" > at runtime, I always get the answer expected. > > > Here is my code: > > (define-syntax (m stx) > (syntax-case stx () > [(_ (hash-table 'name n m ...)) > #'(symbol->string n)] > [(_ (hash-table x0 x1 ...)) > #'"..."] > [(_ (hash-table ('name n) (k v) ...)) > #'"FOO"] > [(_ (hash-table (k v) ...)) > #'"BAM"] > [(_ (hash-table (k0 v0) (k1 v1) ...)) > #'"BAZ"] > [(_ (hash-table x ...)) > #'"COMMON"] > [x #'"WHY"])) > > (define (define-person . fields) > (for/hash ([k '(name e-mail nickname)] > [field fields]) > (values k field))) > > (define person (define-person 'my-name 'my-email 'my-nickname)) > > ; gives why (why nothing before matches ?) > (m person) > > ; my-email > (m (define-person 'my-name 'my-email 'my-nickname)) > > ; gives my-name > (m (hash > 'name 'my-name > 'e-mail 'my-email > 'nickname 'my-nickname)) > > ; gives my-nickname > (m (hash > 'nickname 'my-nickname > 'name 'my-name > 'e-mail 'my-email)) > > > -- > You received this message because you are subscribed to the Google Groups > "Racket Users" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/racket-users/82364adf-fe5d-4c6f-bf33-51852c423371o%40googlegroups.com > <https://groups.google.com/d/msgid/racket-users/82364adf-fe5d-4c6f-bf33-51852c423371o%40googlegroups.com?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "Racket Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/racket-users/CADcuegt1-aR-Bi-Reb-gGouj8sCo%2B7Zun60R3HgUUh0YxKx%2BmA%40mail.gmail.com.
