[Chicken-janitors] #869: xsubstring with negative `from' argument returns empty string

[Chicken Trac]

#869: xsubstring with negative `from' argument returns empty string
---------------------------------+------------------------------------------
 Reporter:  mario                |       Owner:       
     Type:  defect               |      Status:  new  
 Priority:  major                |   Milestone:       
Component:  core libraries       |     Version:  4.7.x
 Keywords:  srfi-13, xsubstring  |  
---------------------------------+------------------------------------------
 The reference implementation of SRFI-13 gives an example of
 {{{xsubstring}}} with a negative {{{from}}} argument:

 {{{
 (xsubstring "abcdef" -2) => "efabcd"
 }}}

 In chicken:

 {{{
 $ csi -nq -R srfi-13
 #;1> (xsubstring "abcdef" -2)
 ""
 }}}

 Gauche and Guile produce {{{"efabcd"}}} (they don't seem to use the
 SRFI-13 reference implementation code).

-- 
Ticket URL: <http://bugs.call-cc.org/ticket/869>
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