Adds intersection types as a better way to handle the the case
when restrict cannot structurally intersect two types (e.g. when
you learn within a polymorphic function a variable x of type A
is also an Integer, but we dont know how A relates to Integer).
This allows for non-lossy refinements of type info while typechecking.
This pull request is largely a renaming effort to clean up the TR codebase. There are two primary things I wanted to change:
1. Replace all occurrences of "filter" with "prop" or "proposition"
- The word "filter" is a meaningless opaque term at this point in the Typed Racket implementation. If anything, it just adds confusion to why things are the way the are. We should use "proposition" instead, since that's what they actually are.
2. Avoid using "Top" and "Bottom" in both the type and proposition realm.
- Currently the top type is called Univ and the bottom type is called bottom, while the top proposition is called Top and the bottom proposition is called Bot. This is just unnecessarily confusing, doesn't really line up w/ the user-space names, and doesn't line up with the names we use in TR formalisms. Worse, all of the top types of primitive types---e.g. the type of all structs, StructTop--- use Top, so it is really easy to get confused about what name to use for these sorts of things.
With these issues in mind, I made the following changes to names:
Top -> TrueProp
Bot -> FalseProp
TypeFilter -> TypeProp
NotTypeFilter -> NotTypeProp
AndFilter -> AndProp
OrFilter -> OrProp
-filter t o -> -is-type o t
-not-filter t o -> -not-type o t
FilterSet -> PropSet
NoFilter -> #f
NoObject -> #f
-FS -> -PS
-top -> -tt
-bot -> -ff
implied-atomic? q p -> implies-atomic? p q
filter-rec-id -> prop-rec-id
-no-filter -> -no-propset
-top-filter -> -tt-propset
-bot-filter -> -ff-propset
-true-filter -> -true-propset
-false-filter -> -false-propset
PredicateFilter: -> PredicateProp:
add-unconditional-filter-all-args add-unconditional-prop-all-args
This is used for functions with a single argument imported with
`require/typed`, and avoids unneccessary checks. This produces a
3x speedup on the following benchmark:
#lang racket/base
(module m racket/base
(provide f)
(define (f x) x))
(module n typed/racket/base
(require/typed
(submod ".." m)
[f (-> Integer Integer)])
(time
(for ([x (in-range 1000000)])
(f 1) (f 2) (f 3) (f 4))))
(require 'n)
on top of the previous improvment from using `unsafe-procedure-chaperone`
and `procedure-result-arity`.
New strategy for compiling the (-> Any Boolean) type to a contract.
When possible, uses `struct-predicate-procedure?` instead of
wrapping in `(-> any-wrap/c boolean?)`.
Makes exceptions for untyped chaperones/impersonators over struct predicates;
those are always wrapped with `(-> any-wrap/c boolean?)`.
This change also affects (require/typed ... [#:struct ...]), but not #:opaque
Most unit forms are supported, including most of the "infer" forms that
infer imports/exports/linkages from the current context.
Notably, none of the structural linking forms for units are supported, and
`define-unit-binding` is also currently unsupported.
Allow more cases that are allowed for ordinary function
contracts and explicitly error instead of internal errors
for other cases.
Closes Github Issue #50
When exporting row polymorphic functions from TR, just
use absent clauses to ensure that TR won't accidentally
try to add pre-existing fields/methods. No sealing is
needed because the typechecker enforces parameteric use
of the class.
