> On Mar 20, 2018, at 11:51 PM, Alex Knauth <alexan...@knauth.org> wrote:
>
>
>
>> On Mar 19, 2018, at 11:37 AM, David Storrs <david.sto...@gmail.com> wrote:
>>
>> This does not work:
>
>> (define user (hash 'name "bob" 'job (hash 'type 'dev 'id 112)))
>> (match user
>> [(hash-table ('name name) ('job (hash-table 'type type 'id id)))
>> (displayln name)
>> (displayln type)
>> (displayln id)])
>> ; id49: unbound identifier;
>> ; also, no #%top syntax transformer is bound
>> ; in: id49
>> ; [,bt for context]
>
> Jos Koot already found the problem, but why is this error message so
> horrible? This seems like a bug in match.
By the way, this is the same error message as this issue:
https://github.com/racket/racket/issues/1964
<https://github.com/racket/racket/issues/1964>
#lang racket
(match (list 1 1)
[(list-no-order x x)
x)]
... signals the error
x7: unbound identifier;
also, no #%top transformer is bound in: x7
Since `hash-table` patterns turn into `list-no-order` patterns, there problem
are two problems that combine to make this:
- the secret feature of `hash-table` makes it mean something you never meant
- `list-no-order` never checks for duplicate identifiers to throw a proper
error message
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