Implement dolist and add tests

lib/Minilisp.pm

@@ -1150,6 +1150,47 @@ sub macro_dotimes {
 }
 $macros{dotimes} = \&macro_dotimes;
 
+sub macro_dolist {
+  my $ts = shift;
+
+  slurp_token($ts, LPAREN, "Expected ( after dolist");
+
+  my $var = slurp_token($ts, IDENT, "Expected identifier for var in dolist")->{value};
+
+  my $list_expr = parser_expr($ts);
+
+  my $result_expr = sub { undef };
+  $result_expr = parser_expr($ts) unless peek_token($ts, RPAREN);
+
+  slurp_token($ts, RPAREN, "Expected ) after list-form or result-form in dolist");
+
+  my $body = macro_progn($ts);
+
+  return create_block(
+    "nil",
+    sub {
+      my $octx = shift;
+
+      my $lst = $list_expr->($octx);
+
+      die "Expected list in dolist"
+        unless ref($lst) eq "ARRAY";
+
+      my $ictx = ctx_create($octx);
+
+      foreach my $e (@$lst)
+        {
+          ctx_set($ictx, $var, $e);
+          $body->($ictx);
+        }
+
+      ctx_set($ictx, $var, undef);
+      return $result_expr->($ictx);
+    }
+  );
+}
+$macros{dolist} = \&macro_dolist;
+
 sub compile {
   my ($term) = @_;
   my @tokens = tokenize($term);

t/dolist.t

@@ -0,0 +1,31 @@
+(plan 5)
+
+(expect "dolist - body is evaluated with every element"
+        (let ((lst (list 1 2 5 'cool 'list 'bro nil))
+              (lst-expected (list nil 'bro 'list 'cool 5 2 1))
+              (lst-actual (list)))
+          (dolist (it lst)
+            (set lst-actual (cons it lst-actual)))
+          (equal lst-expected lst-actual)))
+
+(expect "dolist - body is not evaluated if list is empty"
+        (equal 'ok
+               (catch 'test
+                 (dolist (e (list))
+                   (throw 'test 'fail))
+                 'ok)))
+
+(expect "dolist - result form is evaluated"
+        (equal 'ok
+               (dolist (e (list 1) 'ok))))
+
+(expect "dolist - returns nil if no result form"
+        (null (dolist (e (list 1)))))
+
+(expect "dolist - var is bound to nil during result form"
+        (equal 'ok
+               (catch 'test
+                 (dolist (e (list 'fail)
+                            (unless (null e)
+                              (throw 'test 'fail))))
+                 'ok)))