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{ # 0 0 f f T{ # 1 0 { # { "-test" } T{ # f } T{ # f } T{ # f } T{ # f } T{ # f } T{ # f } T{ # f } T{ # f }... } } 0 T{ # { T{ # 0 32 f f T{ # 0 0 { T{ # f } T{ # f } T{ # f } T{ # f } T{ # f } T{ # f } T{ # f } T{ # f } } } 0 T{ # { T{ # 0 12 f f T{ # 1 0 { # # T{ ... ... } T{ ... ... } T{ ... ... } T{ ... ... } T{ ... ... } T{ ... ... } } } 0 "( no name )" } T{ # 12 20 f f T{ # 0 0 { T{ ... ... } T{ ... ... } T{ ... ... } T{ ... ... } T{ ... ... } T{ ... ... } T{ ... ... } T{ ... ... } } } 2 T{ # { T{ ... ... ... ... ... ... ... ... } 0 0 } 1 } # } T{ # 20 32 f f T{ # 1 0 { # # T{ ... ... } T{ ... ... } T{ ... ... } T{ ... ... } T{ ... ... } T{ ... ... } } } 0 "( no name )" } } 3 } } 0 0 } 1 } } T{ # T{ # T{ # f f # } # } } T{ # 32 f # } T{ # 32 f # } READY