19 Dec
2006
19 Dec
'06
3:50 p.m.
On Tue, Dec 19, 2006 at 08:42:06PM +0000, Neil Mitchell wrote:
Lack of mutable state, referentially transparent and laziness all help with equational reasoning. Inlining is much easier in a lazy language - and inlining is really handy for equational reasoning.
Imagine:
not_term = non_term f x = 12
Now evaluating:
main = f non_term
In a lazy language the value is always 12, in a strict language its always _|_. Now let's inline f:
main = 12
In a lazy language the value is still 12, in a strict language the value has changed.
I don't know if any actual language does this, but your inlining problem can be solved by letting _|_ = arbitrary behaivor. (Of course, I would want a debugging option that gives errors on all arbitrary behaivior.)