let sfwRoot = Opt.( Sys.getenv_opt("FNM_DIR") or { let home = Sys.getenv_opt("HOME") |> Opt.orThrow("There isn't $HOME environment variable set."); Filename.concat(home, ".fnm"); } ); let nodeVersions = Filename.concat(sfwRoot, "node-versions"); let currentVersion = Filename.concat(sfwRoot, "current"); let downloads = Filename.concat(sfwRoot, "downloads");