Eliminate Side Effects When Loading Files

[saulshanabrook]

When we try to run lein check or lein doc it raises a bunch of exceptions, because the instruction files modify global state and the problem files actually try to run the problems, when they are loaded.

To fix this, it might make sense to eliminate global state and remove side effects from loading files.

[Vaguery]

This is also a problem with lein midje, since MIdje checks everything in /src and /test, and thus loads all those overlapping global doodads.