syntax: read and print [. x] and [. @x].

* lib.c (obj_print_impl): Handle (dwim . atom) syntax
by printing [. atom].  Note that (dwim . @var)
and (dwim . @(expr)) already print as [. @var]
and [. @(expr)]; this is not new. But none of these
forms are supported by reading without the
accompanying change to the parser.

* parser.y (dwim): Handle the [. expr] and [ . expr]
syntax, so that forms like [. a] and [. @a] have
print-read consistency. The motivation is to be
able to [. @args] in pattern matching to match a
DWIM forms; I tried that and was surprised to have it
blow up in my face.

* tests/012/readprint.tl: New test file. Future
printer/parser changes will be tested here. Historically,
changes to the syntax have not been consistently
unit-tested.

* y.tab.c.shipped: Regenerated.

1 files changed, 7 insertions, 0 deletions

diff --git a/tests/012/readprint.tl b/tests/012/readprint.tl
new file mode 100644
index 00000000..cf70320a
--- /dev/null
+++ b/tests/012/readprint.tl
@@ -0,0 +1,7 @@
+(load "../common")
+
+(mstest
+  '[ . a] "[. a]"
+  '[. a] "[. a]"
+  '[ . @a] "[. @a]"
+  '[. @a] "[. @a]")