The die word was called by the library. Unless you called it yourself, you have triggered a bug in Factor. Please report. Starting low level debugger... Basic commands: q -- continue executing Factor - NOT SAFE im -- save image to fep.image x -- exit Factor Advanced commands: d -- dump memory u -- dump object at tagged . -- print object at tagged t -- toggle output trimming s r -- dump data, retain stacks .s .r .c -- print data, retain, call stacks e -- dump environment g -- dump generations data -- data heap dump words -- words dump tuples -- tuples dump refs -- find data heap references to object push -- push object on data stack - NOT SAFE code -- code heap dump READY ==== DATA STACK: T{ prettyprint.sections:block 0 0 f f T{ hashtables:hashtable 1 0 { io.styles:presented { "-test" } T{ hashtables.private:tombstone f } T{ hashtables.private:tombstone f } T{ hashtables.private:tombstone f } T{ hashtables.private:tombstone f } T{ hashtables.private:tombstone f } T{ hashtables.private:tombstone f } T{ hashtables.private:tombstone f } T{ hashtables.private:tombstone f }... } } 0 T{ vectors:vector { T{ prettyprint.sections:flow 0 12 f f T{ hashtables:hashtable 0 0 { T{ hashtables.private:tombstone f } T{ hashtables.private:tombstone f } T{ hashtables.private:tombstone f } T{ hashtables.private:tombstone f } T{ hashtables.private:tombstone f } T{ hashtables.private:tombstone f } T{ hashtables.private:tombstone f } T{ hashtables.private:tombstone f } } } 0 T{ vectors:vector { T{ prettyprint.sections:text 0 2 f f T{ hashtables:hashtable 1 0 { io.styles:presented syntax:{ T{ ... ... } T{ ... ... } T{ ... ... } T{ ... ... } T{ ... ... } T{ ... ... } } } 0 "{" } T{ prettyprint.sections:inset 2 10 f f T{ hashtables:hashtable 0 0 { T{ ... ... } T{ ... ... } T{ ... ... } T{ ... ... } T{ ... ... } T{ ... ... } T{ ... ... } T{ ... ... } } } 2 T{ vectors:vector { T{ ... ... ... ... ... ... ... ... } 0 0 } 1 } syntax:t } T{ prettyprint.sections:text 10 12 f f T{ hashtables:hashtable 1 0 { io.styles:presented syntax:} T{ ... ... } T{ ... ... } T{ ... ... } T{ ... ... } T{ ... ... } T{ ... ... } } } 0 "}" } } 3 } } 0 0 } 1 } } T{ io.styles:ignore-close-stream T{ io.encodings:encoder T{ io.streams.c:c-writer f f # } io.encodings.utf8:utf8 } } T{ generic.math:no-math-method 12 f math:<= } T{ generic.math:no-math-method 12 f math:<= } READY