Implement \(1) capture syntax

lib/SAFE.setting

@@ -171,8 +171,10 @@ my class Capture {
     method Capture () { self }
     method list () { @( Q:CgOp { (box Parcel (getslot positionals fvarlist
         (@ {self}))) } ) }
-    method hash () { unitem( Q:CgOp { (box Hash (getslot named varhash
-        (@ {self}))) } // {} ) }
+    method hash () { unitem( Q:CgOp {
+        (letn h (getslot named varhash (@ {self}))
+          (ternary (== (l h) (null varhash)) {{}} (box Hash (l h))))
+    }) }
 }
 # }}}
 # Scalar types {{{

src/niecza

@@ -49,6 +49,22 @@ sub mkstringycat($/, *@strings) {
 }
 
 augment class NieczaActions {
+method capture($ ) {}
+method capterm($/) {
+    my @args;
+    if $<capture> {
+        my $x = $<capture>[0]<EXPR>.ast;
+        if $x.^isa(::Op::SimpleParcel) {
+            @args = @($x.items);
+        } else {
+            @args = $x;
+        }
+    } elsif $<termish> {
+        @args = ::Op::Paren.new(|node($/), inside => $<termish>.ast);
+    }
+    make ::Op::CallSub.new(|node($/), invocant => mklex($/, '&_make_capture'),
+        args => @args);
+}
 method process_nibble($/, @bits, $prefix?) {
     my @acc;
     for @bits -> $n {