Here is a follow on problem as I'm going through the tutorial: obj does not work and the error message seems to access memory not involved with the obj.
arc> (printlst alist)
ARR(1)="PARSE ; PARSE OUTPUT OF ^%RFIND INTO RSD/RTN/TAG"
ARR(2)=" N ARR,FND,I,RSD,RTN,STOP,TXT"
ARR(3)=" W !!,"PASTE""
ARR(4)=" F R !,X:15 Q:'$T S ARR($I(ARR))=X"
ARR(5)=" K RSDS"
""
arc> (= codes (obj "Boston" 'bos "San Francisco" 'sfo "Paris" 'cdg))
Error: "list-ref: contract violation\n expected: exact-nonnegative-integer?\n given: '(((codes (obj \"Boston\" (quote bos . nil) \"San Francisco\" (quote sfo . nil) \"Paris\" (quote cdg . nil) . nil) . nil) . nil))\n argument position: 2nd\n other arguments...:\n '(\"\\nARR(1)=\\\"PARSE ; PARSE OUTPUT OF ^%RFIND INTO RSD/RTN/TAG\\\"\" \"\\nARR(2)=\\\" N ARR,FND,I,RSD,RTN,STOP,TXT\\\"\" \"\\nARR(3)=\\\" W !!,\\\"PASTE\\\"\\\"\" \"\\nARR(4)=\\\" F R !,X:15 Q:'$T S ARR($I(ARR))=X\\\"\" \"\\nARR(5)=\\\" K RSDS\\..."
arc>
Judging by that error message, it looks like the variable "=" or one of its dependencies might have been reassigned somewhere along the line. The second argument in that error message indicates that = is getting hold of your read-in data somehow, so it might be something you've defined for processing this data.
The dependencies of = include expand=list, expand=, map, pair, and setforms (among others), so if any of these has been overwritten, it might do something like what you're seeing.
By the way, I think if you're not using Anarki, there's a known bug in (readline ...) where it will spuriously combine each empty line with the following line (https://sites.google.com/site/arclanguagewiki/arc-3_1/known-...). Maybe this could explain the extra \n you're getting.