gistfile1.txt

]=> (define-package :foo)
#<package 0x12e9fc0 >
]=> (in-package :foo)
#<package 0x12e9fc0 >
]=> +
debugger invoked on error:
  Unbound variable
    :object: (+ . #<environment 0x12b3f30 >)

trace buffer:
    EVAL (dfsch:define-package :foo)
     @ dfsch-user:*console-io*:1
  APPLY #<primitive 0x7f0cf2ad3060 define_package> (:lazy)
      (:foo)
    EVAL :foo
    EVAL (dfsch:in-package :foo)
     @ dfsch-user:*console-io*:2
  APPLY #<primitive 0x7f0cf2ad30a0 in_package> (:lazy)
      (:foo)
    EVAL :foo
    EVAL +
  APPLY #<primitive 0x7f0cf28743a0 enter_debugger> ()
      (#<error 0x12ecf00 :object (+ . #<environment 0x12b3f30 >) :message "Unbound variable">)

restarts:
   0: [abort] Return to reader
   1: [dfsch-user:quit] Exit interpreter
dbg1> 0
]=> (dfsch:use-package :dfsch)
()
]=> (unintern '+)
#<uninterned-symbol 0x12ecf34 +>
]=> +
#<primitive 0x7f0cf2ad54c0 plus>