principle of least surprise

Thomas Lindgren thomasl_erlang@REDACTED
Tue Nov 22 15:49:39 CET 2005

--- Alex Arnon <alex.arnon@REDACTED> wrote:

> So if we keep a "side-effect allowed" flag stack
> along (or as part of) the
> process stack, implementation should be easy... or
> would it? :)

I expect this to be doable; perhaps you can merely
save/restore the side effect flag when necessary.

I would like two things, though: 

1. An implementation-independent "semantics" of deep
guards, where the principles for when side-effects are
permitted and not are made clear. As simple as
possible while still permitting deep guards.

2. An efficient implementation of these principles.


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