[Chicken-janitors] [Chicken-bugs] #433: symbols should be immutable

[Chicken Scheme]

#433: symbols should be immutable
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 Reporter:  sjamaan                                             |       Owner:  
     
     Type:  defect                                              |      Status:  
new  
 Priority:  critical                                            |   Milestone:  
     
Component:  core libraries                                      |     Version:  
3.0.0
 Keywords:  symbols, mutation, destructive procedures, strings  |  
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 When using {{{->string}}} on a symbol and calling a destructive string
 procedure on the result, you mutate the original symbol everywhere it's
 used.  After that, the mutated symbol is not {{{eq?}}} to the same symbol
 when made afresh.

 {{{
 #;1> (define x 'TEST)
 #;2> (define y 'test)
 #;3> (define z 'test)
 #;4> (string-upcase! (->string y))
 "TEST"
 #;5> (eq? x y)
 #f
 #;6> (eq? y z)
 #t
 #;7> x
 TEST
 #;8> y
 TEST
 #;9> (eq? x 'test)
 #f
 #;10> (eq? x 'TEST)
 #t
 #;11> (eq? y 'TEST)
 #f
 #;12> (eq? y 'test)
 #f
 }}}

 Not sure what the solution should be.  Perhaps {{{->string}}} should just
 make a copy, or the destructive procedures should make a copy when invoked
 on an immutable string, or refuse to operate on immutable strings.

-- 
Ticket URL: <http://trac.callcc.org/ticket/433>
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