Report source name when accessing a variable too early, and allow
multiple returns (based on continuation capture) for the right-hand
side of a `letrec`.
The repair directly implements `letrec` as needed in terms of `let`
and `set!`, instead of relying on Chez Scheme's `letrec`, unless
right-hand sides are simple enough. Implementing `letrec` that way
risks losing Chez Scheme optimizations, but schemify takes care
of many improvements already.
Get more of the benefit of traditional Racket's lazy bytecode
unmarshaling by using an explicit `fasl->s-exp` stap on the serialized
form of syntax objects. This approach also avoids generating pointless
machine code for constructing the serialized form, effectively using
`fasl->s-exp` as an interpreter. The result is significantly smaller
".zo" files for RacketCS and slightly faater load times.
+ overwrite any failed download attempts (after catching the exception &
retrying the download)
+ pause between download attempts
+ ensure that `(get-test-file)` always returns a file that exists
+ check whether downloaded file is empty
+ delete bad downloaded files
+ skip the test if download fails
* Add support for space-efficient vector and arrow contracts.
When an eleventh contract would be applied to a function or vector,
switch representation for the wrapper and try eliding redundant
checks. The resulting value keeps a constant number of
chaperone/impersonator wrappers regardless of the number of contracts
applied to it, and won't run any (provably) redundant checks.
This avoids a pathological case where, e.g., a function crosses a
boundary inside a loop, and gets wrapped N times (or worse, 2^N).
The optimization for function contracts currently only applies for
fixed-arity functions and contracts, and only for functions with known
result-arity of 1. These limitations are not fundamental.
Checking specific checks is not as optimized as for regular arrow
contracts yet. (Specifically: arity-specific wrappers and
tail-marks-match support is missing.) Again, not a fundamental
limitation.
Further described in the OOPSLA 2018 Paper: "Collapsible Contracts: Fixing a Pathology of Gradual Typing"
In collaboration with Ben Greenman, Christophe Scholliers, Robby Findler, and Vincent St-Amour.
Recent changes to adapt cm to cross-multi mode also attempted to
improve dependency checking to avoid prematurely committing to
compiling an old dependency, but that improvement was broken.
The multi-cross mode, don't rewrite a machine-indepedent file
by recompiling it to itself. This shouldn't matter, but not
touching files makes the result cleaner.
When a `[case-]lambda` form's only free variables are at the module
level, the Schemified form is a `[case-]lambda` form whose only free
variables are in an enclosing `lambda` for a linklet. Since those are
not completely closed, to make the allocation pattern consistent with
traditional Racket, Chez Scheme needs a hint to allocate the closures
once per linklet instantiation.
When an ephemeron is accessed through a weak mapping from the same key
that is used in the ephemeron, and when the key is not otherwise
reachable, there can be a race between extracting the value from the
ephemeron and performing a GC that reclaims the key. Avoid that race
by supplying the key back to `ephemeron-value`, which ensures that the
key remains reachable until the value is extracted.
In many cases, supplying the key as the second argument would also
work --- since that argument is used as a replacement value when the
key is inaccessible, but the key can't become inaccessible if it's
pending as a replacement value. A separarate optional argument to
`ephemeron-value` seems clearer and more general, though.
Avoid retaining namespaces that are created to gather runtime paths.
If expansion generates a lot of instances with a lot of type
information, for example, this repair can save a lot of space.
