Currently functions have unfettered access to variables in higher scopes - be it the program's globals, or the caller's variables. This is a really stupid design decision that should be changed.

Proposed solution:

• Limit functions to accessing only their local variables (and args/statics)
• To use global variables, one must explicitly declare their use with!global $varname
• The construct should probably be limited to the function's top-level scope (can't be put inside!if or loops)

Things to consider:

• Should!global $var and!global &var be equivalent, or should the first one create a copy of the global variable in local scope (instead of adding a reference)?
• What should happen when a function calls!global &var and&var hasn't been yet set?