Add rudimentary support for lists

lib/Minilisp.pm

@@ -80,6 +80,18 @@ sub tokenize {
   return @tokens;
 }
 
+sub lisp_format {
+  my $e = shift;
+  if (ref($e) eq "ARRAY")
+    {
+      return "(" . join(" ", map { lisp_format($_) } @$e) . ")";
+    }
+  else
+    {
+      return "$e";
+    }
+}
+
 my %stdctx = (
   '+' => sub {
     my $sum = 0;
@@ -103,7 +115,12 @@ my %stdctx = (
   },
   'write-line' => sub {
     my $e = shift;
-    print "$e\n";
+    print lisp_format($e) . "\n";
+    return undef;
+  },
+  'write' => sub {
+    my $e = shift;
+    print lisp_format($e);
     return undef;
   },
   'null' => sub { my ($a) = @_; return ! defined $a; },
@@ -169,7 +186,15 @@ my %stdctx = (
   # string length
   'length' => sub {
     my ($a) = @_;
-    return length($a);
+
+    if (ref($a) eq "ARRAY")
+      {
+        return scalar(@$a);
+      }
+    else
+      {
+        return length($a);
+      }
   },
 
   # Bitwise operations
@@ -199,6 +224,12 @@ my %stdctx = (
     return ~$v;
   },
 
+  # Lists
+  'list' => sub { return [ @_ ]; },
+  'first' => sub { return (shift)->[0]; },
+  'second' => sub { return (shift)->[1]; },
+  'nth' => sub { my ($idx,$list) = @_; return $list->[$idx]; },
+
   # Constants
   't' => 1,
   'f' => 0,