Can't do check completely statically, because phase of comparison
is expression (and even default is slightly unpredictable).
So instead compute whether check would succeed for likely phase
offsets, and use list of ok offsets as run-time fast path (memv
instead of identifier-binding).
Changed backtracking algorithm, runtime representations
- syntax classes, ~describe no longer implicitly commit
- ~describe no longer delimits effect of cut
Added keyword & optional args for stxclasses
Added ~do and #:do, ~post, ~commit and #:commit,
~delimit-cut and #:no-delimit-cut
Added syntax/parse/debug, syntax/parse/experimental/*
- expr/c for contracting macro sub-expressions
moved from syntax/parse to syntax/parse/experimental/contract
- syntax class reflection (~reflect, ~splicing-reflect)
- eh-alternative-sets (~eh-var)
- provide-syntax-class/contract
(only for params, not attrs so far)
Changed ~fail to not include POST progress (#:fail still does)
old (~fail _) is now (~post (~fail _))
Made msg argument of ~fail optional
Removed generic "repetition constraint violated" msg
Removed atom-in-list stxclass
Removed unnecessary datum->syntax on cdr of pair pattern
massive improvements to long-list microbenchmarks
Optimization: integrable syntax classes (id, expr, keyword)
need better measurements
Optimization: ad hoc elimination of head/tail choice point
for (EH ... . ()) patterns
Added unstable/wrapc (proc version of expr/c)
