# A calculator in a single expression of Python
(tk := __import__("tkinter")) and (bt_draw := lambda key, col, lin:
(bt := tk.Button(window, text=key, command=lambda: bt_press(key)))
and bt.grid(column=col + 1, row=lin + 1)) and (update := lambda t:
disp.config(text=t)) and (bt_press := lambda key: update("" if key
== "C" else disp["text"][:-1] if key == "<" else str(round(eval(
disp["text"]), 6)) if key == "=" else disp["text"] + key)) and (
window := tk.Tk()) and window.title("TKalc") or (disp := tk.Label(
window, text="")) and disp.grid(column=0, row=0, columnspan=5) or (
bt_list := [bt_draw(k, n % 4 + 1, n // 4 + 1) for n, k in enumerate
("()C<789/456*123-.0=+")]) and window.mainloop()
Elegant (line of) code
