Turns out this was not a very useful idea, and semantically tricky to
boot.
This reverts commit 24bf130fd1, and makes
the following additional changes:
* module/ice-9/optargs.scm (parse-lambda-case, let-optional)
(let-optional*, let-keywords, let-keywords*):
* module/language/tree-il.scm: (<lambda-case>, parse-tree-il)
(unparse-tree-il, tree-il->scheme, tree-il-fold,
make-tree-il-folder)
(post-order!, pre-order!):
* module/language/tree-il/analyze.scm (analyze-lexicals):
* module/language/tree-il/compile-glil.scm (compile-glil):
* module/language/tree-il/inline.scm (inline!): Remove all traces of
#:predicate from tree-il.
* module/ice-9/psyntax.scm (build-simple-lambda, build-lambda-case)
(chi-lambda-case): Adapt to tree-il change.
* module/ice-9/psyntax-pp.scm: Regenerated.
* module/language/brainfuck/compile-tree-il.scm (compile-body):
* module/language/ecmascript/compile-tree-il.scm (comp, comp-body):
* test-suite/tests/tree-il.test: Adapt to tree-il change.
* doc/ref/api-procedures.texi (Case-lambda): Remove mention of
#:predicate.