Common Lisp, 8 bytes

Shorter than the other Common Lisp answer :-)

#.(loop)

Loop while reading your form.

Also, for an implementation-dependant approach with still 8 bytes, use:

#.(quit)

... or,

#.(exit)

When you call (compile-file "crash.lisp"), Clozure CL (first line) and Steel Bank Common Lisp (second line) mysteriously "crash".

I am still trying to find a way to really crash the environment, but it is really hard. All I get is a nice interaction with the debugger.

Common Lisp, 8 bytes

Shorter than the other Common Lisp answer :-)

#.(loop)

Loop while reading your form.

The Common Lisp standard has no mention of a portable way to make it crash, so I guess we need to have an implementation-defined way. Still 8 bytes:

#.(quit) ; ccl

... or,

#.(exit) ; sbcl

When you call (compile-file "crash.lisp"), the environments mysteriously "crash".

Joking apart, I am still trying to find a way to really crash the environment (and shortly), but it is really hard. All I get is a nice interaction with the debugger.

Common Lisp, 8 bytes

Shorter than the other Common Lisp answer :-)

#.(loop)

Loop while reading your form.

Also, for an implementation-dependant approach, use:

#.(quit)

When you call (compile-file "crash.lisp"), Clozure CL mysteriously "crash".

Common Lisp, 8 bytes

Shorter than the other Common Lisp answer :-)

#.(loop)

Loop while reading your form.

Also, for an implementation-dependant approach with still 8 bytes, use:

#.(quit)

... or,

#.(exit)

When you call (compile-file "crash.lisp"), Clozure CL (first line) and Steel Bank Common Lisp (second line) mysteriously "crash".

I am still trying to find a way to really crash the environment, but it is really hard. All I get is a nice interaction with the debugger.

Common Lisp, 8 bytes

Shorter than the other Common Lisp answer :-)

#.(loop)

Loop while reading your form.

Common Lisp, 8 bytes

Shorter than the other Common Lisp answer :-)

#.(loop)

Loop while reading your form.

Also, for an implementation-dependant approach, use:

#.(quit)

When you call (compile-file "crash.lisp"), Clozure CL mysteriously "crash".