Implement dotimes and add tests

lib/Minilisp.pm

@@ -1112,6 +1112,44 @@ sub macro_throw {
 }
 $macros{throw} = \&macro_throw;
 
+sub macro_dotimes {
+  my $ts = shift;
+
+  slurp_token($ts, LPAREN, "Expected ( after dotimes");
+
+  my $var = slurp_token($ts, IDENT, "Expected identifier for var in dotimes")->{value};
+
+  my $count_expr = parser_expr($ts);
+
+  my $result_expr = sub { undef };
+  $result_expr = parser_expr($ts) unless peek_token($ts, RPAREN);
+
+  slurp_token($ts, RPAREN, "Expected ) after count-form or result-form in dotimes");
+
+  my $body = macro_progn($ts);
+
+  return create_block(
+    "nil",
+    sub {
+      my $octx = shift;
+
+      my $n = $count_expr->($octx);
+
+      my $ictx = ctx_create($octx);
+
+      for(my $i = 0; $i < $n; $i++)
+        {
+          ctx_set($ictx, $var, $i);
+          $body->($ictx);
+        }
+
+      ctx_set($ictx, $var, $n);
+      return $result_expr->($ictx);
+    }
+  );
+}
+$macros{dotimes} = \&macro_dotimes;
+
 sub compile {
   my ($term) = @_;
   my @tokens = tokenize($term);

t/dotimes.t

@@ -0,0 +1,30 @@
+(plan 5)
+
+(expect "dotimes - executes body n times"
+        (let ((pings 0))
+          (dotimes (i 5)
+            (set pings (+ 1 pings)))
+          (equal pings 5)))
+
+(expect "dotimes - evaluates result form"
+        (equal 6
+               (dotimes (i 6 i))))
+
+(expect "dotimes - implicit block nil"
+        (equal 'ok
+               (dotimes (i 6)
+                 (return 'ok))))
+
+(expect "dotimes - body is not evaluated if count is 0"
+        (equal 'ok
+               (catch 'test
+                 (dotimes (i 0)
+                   (throw 'test 'fail))
+                 'ok)))
+
+(expect "dotimes - body is not evaluated if count is negative"
+        (equal 'ok
+               (catch 'test
+                 (dotimes (i -3)
+                   (throw 'test 'fail))
+                 'ok)))