On 12/17/2012 04:32 PM, Matthias Felleisen wrote:
On Dec 17, 2012, at 6:10 PM, Neil Toronto wrote:
`plot' is written in untyped Racket. There's no performance problem with typed
plots at all; in fact, using `plot/typed' from TR code ends up checking exactly
the same contracts for the same plots. `plot/typed' is just another end-user
that happens to re-export everything with types attached.
I don't understand this last part at all. You have
-- an untyped file M
-- a typed file T that imports M and re-exports everything from there with types
How can it possibly be the case that a client C imports T and does NOT pay for
the contracts that T's types impose on the call chain?
That would only happen if client C is untyped. I wouldn't expect an untyped
client to (require plot/typed), but I suppose it could happen.
Wait. This is the line I don't understand:
C is TYPED. It requires T.
T is TYPED. It requires M.
M is UNTYPED.
If c in C calls t in T, this first call does not add any overhead. OK.
But t is really m from M obtained with a require/typed. [Alternatively, it is
redefinition that calls such a function.]
It is this call from t to m that imposes the overhead.
Why are you saying that "There's no performance problem with typed plots at
all"?
Oh! Oh, right... I totally forgot that `require/typed' wraps things in
contracts. Duh.
Yes. So plotting in Typed Racket goes through two contract barriers.
It's a small performance hit compared to the rest of the rendering
pipeline. But it's a performance hit. We can carry on now.
Neil ⊥
_________________________
Racket Developers list:
http://lists.racket-lang.org/dev
