private static Func<double, double[], double> GetOperation(string oper)
{
Operation op = new Operation(oper);
switch (op.Value)
{
case Operation.ADD: return (l, r) => r.Aggregate(l,(a,b) => a + b);
case Operation.MIN: return (l, r) => r.Aggregate(l,(a, b) => a - b);
case Operation.MULT: return (l, r) => r.Aggregate(l,(a, b) => a * b);
case Operation.DIV: return (l, r) => { op.FailIf(r.Last() == 0D, LispError.DIVIDE_BY_ZERO);
return r.Aggregate(l, (a, b) => a / b);
};
case Operation.POW: return (l, r) => {
op.FailIf(r.Count() != 1, LispError.INVALID_ARGS_NUM);
return Math.Pow(l, r[0]);
};
case Operation.AVG: return (l, r) => {
op.FailIf(r.Count() == 0, LispError.INVALID_ARGS_NUM);
return r.Aggregate(l, (a, b) => a + b) / (1 + r.Count());
};
}
return null;
}
