[plt-scheme] Re: hash-has-key?

From: Jay McCarthy (jay.mccarthy at gmail.com)
Date: Fri Apr 17 12:46:14 EDT 2009

The online documentation tracks SVN, and that function was added since
4.1.4. The documentation on your computer is accurate for you. (This
is demonstrated in the version number in the upper right hand corner.)


On Fri, Apr 17, 2009 at 7:18 AM, TPJ <tprimke at gmail.com> wrote:
> On 28 Mar, 01:14, Henk Boom <h... at henk.ca> wrote:
>> Hi, I was looking for a way to test whether or not a hash table has a
>> mapping for a given key. I was surprised not to find anything in the
>> docs (...)
> Interesting. I found hash-has-key? in the PLT Reference
> (http://docs.plt-scheme.org/reference/hashtables.html), but I cannot
> use it:
> Welcome to DrScheme, version 4.1.4 [3m].
> Language: Module; memory limit: 128 megabytes.
>> (define a (make-hash))
>> (hash-has-key? a 'key)
> . . reference to undefined identifier: hash-has-key?
> What's wrong? (I'm new to Scheme and to PLT Scheme.)
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Jay McCarthy <jay at cs.byu.edu>
Assistant Professor / Brigham Young University

"The glory of God is Intelligence" - D&C 93

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