more robust: allow empty root (e.g. via symlink);
#!/usr/bin/env bash
#
# Author: Makarius
#
# DESCRIPTION: setup OCaml via OPAM
set -e
if [ -e "$ISABELLE_OPAM_ROOT/config" ]
then
isabelle_opam switch "$ISABELLE_OCAML_VERSION"
else
isabelle_opam init --no-setup --compiler="$ISABELLE_OCAML_VERSION"
fi
isabelle_opam install zarith