add test demonstrating recursive smartmatch callbacks

t/sugar.t

@@ -0,0 +1,49 @@
+#!/usr/bin/env perl
+use strict;
+use warnings;
+use Test::More;
+
+use List::MoreUtils;
+
+{
+    use smartmatch sub {
+        if (ref($_[1])) {
+            return $_[1]->($_[0]);
+        }
+        else {
+            return $_[1] eq "foo";
+        }
+    };
+
+    ok("a" ~~ any(1, 2, "foo"));
+    ok(!("a" ~~ any(1, 2, 3)));
+}
+
+sub any {
+    my @rvals = @_;
+
+    return sub {
+        my ($lval) = @_;
+
+        my $recurse = get_smartmatch_callback();
+        return List::MoreUtils::any { $recurse->($lval, $_) } @rvals;
+    }
+}
+
+sub get_smartmatch_callback {
+    my $hh = (caller(2))[10];
+    my $engine = $hh ? $hh->{'smartmatch/engine'} : undef;
+
+    my $recurse;
+    if ($engine) {
+        $recurse = eval <<"RECURSE";
+            use smartmatch '$engine';
+            sub { \$_[0] ~~ \$_[1] }
+RECURSE
+    }
+    else {
+        $recurse = sub { $_[0] ~~ $_[1] };
+    }
+}
+
+done_testing;