public static IEnumerable <FuncInfo> GetFuncInfos(IEnumerable <FuncDef> funcDefs, SolverAliases aliasOf, Func <FuncInfo, bool> funcFilter = null) { if (funcFilter == null) { funcFilter = x => true; } return(funcDefs.Select(fd => FuncInfo.Create(fd, aliasOf)).Where(fi => fi != null && funcFilter(fi))); }