OpamPrinter.format_value does not handle precedence #56
Description
Hi,
When passed to OpamPrinter.format_value, the expression (a | b) & c is printed as a | b & c, which is equivalent to a | (b & c). The function does not seem to have any way of printing parentheses (but the corresponding function in opam-format seems to work).
See ocaml/dune#3431.
Thanks!