lib/Tools/ocaml_setup_base

clarified signature

#!/usr/bin/env bash
#
# Author: Makarius
#
# DESCRIPTION: setup OCaml base compiler via OPAM

set -e

if [ -d "$ISABELLE_OPAM_ROOT/$ISABELLE_OCAML_VERSION/bin" ]
then
  isabelle_opam switch -y "$ISABELLE_OCAML_VERSION"
elif [ -e "$ISABELLE_OPAM_ROOT/config" ]
then
  isabelle_opam switch create -y "$ISABELLE_OCAML_VERSION"
else
  mkdir -p "$ISABELLE_OPAM_ROOT"
  cd "$ISABELLE_OPAM_ROOT"
  isabelle_opam init -y --disable-sandboxing --no-setup --compiler="$ISABELLE_OCAML_VERSION"
fi