Write some crazy destructuring macro that can take forms and pluck out data

[Fuco1]

See for example

(cl-defmethod elsa-check-check ((_ elsa-check-lambda-eta-conversion) form scope state)
  (let* ((seq (oref form sequence))
         (arg-list (elsa-form-sequence (nth 1 seq)))
         (body (nthcdr 2 seq)))
    (when (= 1 (length body))
      (let ((fn-form (car body)))
        (when (elsa-form-list-p fn-form)
          (let ((fn-args (cdr (elsa-form-sequence fn-form))))
            (when (and (= (length arg-list) (length fn-args))
                       (-all-p
                        (-lambda ((lambda-arg . fn-arg))
                          (and (elsa-form-symbol-p fn-arg)
                               (eq (elsa-form-name lambda-arg)
                                   (elsa-form-name fn-arg))))
                        (-zip arg-list fn-args)))
              (elsa-state-add-error state
                (elsa-make-notice (format "You can eta convert the lambda form and use the function `%s' directly"
                                          (symbol-name (elsa-form-name fn-form)))
                                  (elsa-form-car form))))))))))

This is quite complicated function which does essentially nothing except check if the body is of length 1 and then compare two lists.

I can imagine something like

(defmacro elsa-match-form (&rest)
  (declare (indent 2))
  )

(elsa-match-form form
    (:symbol (:list args) (&rest body))
  (elsa-match-form body
      ((:list first)) ;; list of one thing which is a list form
    (elsa-match-form first
        (:symbol name)) ;; gives me the symbol form... but all I really care is the name?, maybe I could use (:symbol-name name)
    ...
    ))

Obviously this should be nestable recursively... and maybe with multiple options like pcase. The syntax needs to be very light and only work with the syntax.

[Fuco1]

Something not that bad can be achieved with pcase already out of the box, but it is still not very clear, especially with the "useless" eieio markers

;; pcase matcher
(pcase my-lambda-form
  ((and (pred elsa-form-list-p)
        (eieio (sequence `(,(eieio name) ,lb-args ,(eieio (sequence `(,(eieio (name fn-name)) . ,fn-args)))))))
   (list :name name
         :args lb-args
         :fn-name fn-name
         :fn-args fn-args)))

;; form
(lambda (x) (+ x))

;; reader form
(setq my-lambda-form [eieio-class-tag--elsa-form-list 102 120 nil 6 0
                                 [eieio-class-tag--elsa-type-mixed]
                                 nil unbound
                                 ([eieio-class-tag--elsa-form-symbol 103 109 nil 6 1
                                                                     [eieio-class-tag--elsa-type-mixed]
                                                                     nil unbound lambda]
                                  [eieio-class-tag--elsa-form-list 110 113 nil 6 8
                                                                   [eieio-class-tag--elsa-type-mixed]
                                                                   nil unbound
                                                                   ([eieio-class-tag--elsa-form-symbol 111 112 nil 6 9
                                                                                                       [eieio-class-tag--elsa-type-mixed]
                                                                                                       nil unbound x])]
                                  [eieio-class-tag--elsa-form-list 114 119 nil 6 12
                                                                   [eieio-class-tag--elsa-type-mixed]
                                                                   nil unbound
                                                                   ([eieio-class-tag--elsa-form-symbol 115 116 nil 6 13
                                                                                                       [eieio-class-tag--elsa-type-mixed]
                                                                                                       nil unbound +]
                                                                    [eieio-class-tag--elsa-form-symbol 117 118 nil 6 15
                                                                                                       [eieio-class-tag--elsa-type-mixed]
                                                                                                       nil unbound x])])])