[#CLJ-414] In latest clojure, empty list is neither true nor false - Clojure JIRA

Details

Type: Defect
Status: Closed
Resolution: Declined
Affects Version/s: None
Fix Version/s: Backlog
Component/s: None
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None

Description

In latest Clojure, compiled today:

user> (true? ())
false
user> (false? ())
false

This makes empty collections the only entities in Clojure which are neither true, nor false.
I'm fairly sure () used to be true – is this an intentional change? Googling reveals lots of warnings about the empty list not being false in Clojure.

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Assembla Importer added a comment - 24/Aug/10 12:35 AM

Converted from http://www.assembla.com/spaces/clojure/tickets/414

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Assembla Importer added a comment - 24/Aug/10 12:35 AM Converted from http://www.assembla.com/spaces/clojure/tickets/414

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Assembla Importer added a comment - 24/Aug/10 12:35 AM

bpsm said: You've confused true? and false? with boolean.

Clojure 1.0.1-alpha-SNAPSHOT
user=> (false? '())
false
user=> (true? '())
false
user=> (boolean '())
true
</code></pre>
<pre><code>Clojure 1.1.0
user=> (false? '())
false
user=> (true? '())
false
user=> (boolean '())
true
</code></pre>
<pre><code>Clojure 1.2.0-beta1
user=> (false? '())
false
user=> (true? '())
false
user=> (boolean '())
true

boolean converts its argument to either true or false. nil and false yield false, everything else yields true.
true? and false? do no such conversion, nor should they. Only true is true?. Only false is false?.

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Assembla Importer added a comment - 24/Aug/10 12:35 AM bpsm said: You've confused true? and false? with boolean.

Clojure 1.0.1-alpha-SNAPSHOT
user=> (false? '())
false
user=> (true? '())
false
user=> (boolean '())
true
</code></pre>
<pre><code>Clojure 1.1.0
user=> (false? '())
false
user=> (true? '())
false
user=> (boolean '())
true
</code></pre>
<pre><code>Clojure 1.2.0-beta1
user=> (false? '())
false
user=> (true? '())
false
user=> (boolean '())
true

boolean converts its argument to either true or false. nil and false yield false, everything else yields true. true? and false? do no such conversion, nor should they. Only true is true?. Only false is false?.

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Reporter:

Anonymous

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Dates

Created:

24/Jul/10 9:56 PM

Updated:

24/Aug/10 12:35 AM

Resolved:

24/Aug/10 12:35 AM