This adds #:eager as an option for controlling this behavior.
Using `#:eager 10` is a 2x improvement in performance for configuration 010001
of the suffixtree benchmark from Takikawa et al, POPL 2016.
The default behavior is unchanged. This is configurable because some
programs are much faster when eager checking is performed. For example:
(require racket/contract)
(collect-garbage)
(time (for/sum ([_ 100000])
(vector-ref (contract (vectorof integer? #:eager #t) #(1) 'pos 'neg)
0)))
(collect-garbage)
(time (for/sum ([_ 100000])
(vector-ref (contract (vectorof integer? #:eager #f) #(1) 'pos 'neg)
0)))
The second loop is 3-4 times slower than the first. However, making
the vector much larger will make the difference go the other way.
Made the hash-set chaperones essentially forward the hash chaperone
operations, but now explain them all in terms of set-based operations
in the docs.
Also adjusted value-blame and has-blame? to support late-neg projections
Specifically, remove reliance on procedure-closure-contents-eq? to
tell when a pending check is stronger in favor of usint
contract-stronger?
Also, tighten up the specification of contract-stronger? to require
that any contract is stronger than itself
With this commit, this program gets about 10% slower:
#lang racket/base
(require racket/contract/base)
(define f
(contract
(-> any/c integer?)
(λ (x) (if (zero? x)
0
(f (- x 1))))
'pos 'neg))
(time (f 2000000))
becuase the checking is doing work more explicitly now but because the
checking in more general, it identifies the redundant checking in this
program
#lang racket/base
(require racket/contract/base)
(define f
(contract
(-> any/c integer?)
(contract
(-> any/c integer?)
(λ (x) (if (zero? x)
0
(f (- x 1))))
'pos 'neg)
'pos 'neg))
(time (f 200000))
which makes it run about 13x faster than it did before
I'm not sure if this is a win overall, since the checking can be more
significant in the case of "near misses". For example, with this
program, where neither the new nor the old checking detects the
redundancy is about 40% slower after this commit than it was before:
#lang racket/base
(require racket/contract/base)
(define f
(contract
(-> any/c (<=/c 0))
(contract
(-> any/c (>=/c 0))
(λ (x) (if (zero? x)
0
(f (- x 1))))
'pos 'neg)
'pos 'neg))
(time (f 50000))
(The redundancy isn't detected here because the contract system only
looks at the first pending contract check.)
Overall, despite the fact that it slows down some programs and speeds
up others, my main thought is that it is worth doing because it
eliminates a (painful) reliance on procedure-closure-contents-eq? that
inhibits other approaches to optimizing these contracts we might try.
in particular, when there is a recursive contract, then we check only
some part of the first-order checks and see if that was enough to
distinguish the branches. if it was, we don't continue and otherwise we do
Port `examples`, `interactions`, etc., to use the new `examples`
form of `scribble/examples`. The main intended effect is to ensure
that errors are produced by examples only as specifically
indicated.
- uniformly remove the extra layers of calls to unknown functions for
chapereone-of? checks that make sure that chaperone contracts are
well-behaved (put those checks only in contracts that are created
outside racket/contract)
- clean up and simplify how missing projection functions are created
(val-first vs late-neg vs the regular ones)
- add some logging to more accurately tell when late-neg projections
aren't being used
- port the contract combinator that ->m uses to use late-neg
- port the </c combinator to use late-neg
