Hi,

First of all, Thank You Adam for such an amazing package. I'm just scratching the surface of it but I already see some interesting workflows that org-ql can enable. Not only that but by reading the source code I've learnt a lot (I'm very new to Emacs, so lots to learn).

Awesome!

I noticed some strange behaviour when combining link with or. I've tried to reduce it to the simplest example to reproduce (it was an org-babel file hence the current-buffer; but Github does not allow for attaching of .org files, neither understands what babel is):

* TODO Item 1
+ [[notmuch:id:one-message-id][One Message ID]]
+ [[notmuch:id:two-message-id][Two Message ID]]

* TODO Item 2
:PROPERTIES:
:EMAIL:    [[notmuch:id:three-message-id][Three Message ID]]
:END:
+ [[notmuch:id:one-message-id][One Message ID]]

With the sample file above I try several things:

;; Expect Items 1 & 2. Does return items 1 & 2
(org-ql-select (current-buffer)
  '(link "notmuch:id:one-message-id")
  :action '(org-get-heading t t))

;; Expect Items 1 & 2. Does return items 1 & 2
(org-ql-select (current-buffer)
  '(link :target "notmuch:id:one-message-id")
  :action '(org-get-heading t t))

So the link predicate works as expected. But strange things happen when you want to combine multiple link predicates with either and or or:

;; Expect Item 1, returns nothing
(org-ql-select (current-buffer)
  '(and (link "notmuch:id:one-message-id")
        (link "notmuch:id:two-message-id"))
  :action '(org-get-heading t t))

;; Expect Item 1, returns nothing
(org-ql-select (current-buffer)
  '(and (link :target "notmuch:id:one-message-id")
        (link :target "notmuch:id:two-message-id"))
  :action '(org-get-heading t t))

And with or:

;; Expect Items 1 & 2, returns Item 1
(org-ql-select (current-buffer)
  '(or (link "notmuch:id:one-message-id")
       (link "notmuch:id:three-message-id"))
  :action '(org-get-heading t t))

;; Expect Items 1 & 2, returns Item 1
(org-ql-select (current-buffer)
  '(or (link :target "notmuch:id:one-message-id")
       (link :target "notmuch:id:three-message-id"))
  :action '(org-get-heading t t))

So... I'm missing something; But according to my org-mode I've already been at it for 2 hours without success!

Some more background. I use e-mail a lot, so much that more than half my org-mode TODO items link to e-mails. So I wondered: Why not have a command that finds all TODO items that link to them? aka, backlinks from TODO to emails.

I use notmuch, so I think it is very easy: just combine notmuch-show-get-messages-ids with a query (or (link :target "notmuch:id:....") (link...)). And done. Except for the above. Now I realise (reading the code of org-sidebar) that this is probably a very underperforming way to do it, so I'll give it a go using regular expressions. Will be fun too :)

Nonetheless I'm really curious to understand why the above examples did not work.

I am on org-ql 0.6.1