Macro for writing math expressions with infix syntax. Requires calc, smartparens, dash and s.

cal.el

(defmacro cal (&rest expression)
  "Evaluate algebraic EXPRESSION using calc."
  (let*
      ((expr (with-temp-buffer
               (lisp-mode)
               (insert (->> expression
                         (-map 'pp-to-string)
                         (apply 'concat)
                         (s-replace (rx space) "")))
               ;; Unpack unquote forms applied by the lisp reader.
               (goto-char (point-min))
               (while (search-forward "(\\," nil t)
                 (forward-char -1)
                 (sp-splice-sexp-killing-around))
               (buffer-string)))
       (result (calc-eval expr)))

    (if (listp result)
        (destructuring-bind (pos err) result
          (error "%s\n%s\n%s^"
                 err
                 expr
                 (s-repeat pos " ")))
      (read (s-replace "," "" result)))))