将数学函数包装到R函数中

我想写一个函数，它接受任何用户提供的数学函数（例如x^2），并用它做不同的事情，例如：

#-----------------nonworking code---------------------
foo <- function(FUN, var){
      math_fun <- function(x){
           FUN
      }
   curve(math_fun, -5, 5)     #plot the mathematical function
   y = math_func(var)         #compute the function based on a user provided x value.
   points(x=var, y=y)         #plot the value from the last step.
}

#A user can use the function defined above in a way as shown below:
Function <- x^2 + x
foo(FUN=Function, var = 2)

---

但我不知道我到底该如何实现这一点。。。如果有人能帮我解决至少部分问题，那就太好了。谢谢

比这简单多了。用户定义函数的定义中应包含参数，例如

function（x）x^2+x

而不是

x^2+x

。然后可以直接传递和调用它：

foo <- function(math_fun, var){

   curve(math_fun, -5, 5)  #plot the mathematical function
   y = math_fun(var)       #compute the function based on a user provided x value
   points(x=var, y=y)      #plot the value from the last step.
}

#A user can use the function defined above in a way as shown below:
Function <- function(x) x^2 + x
foo(Function, var = 2)

---

foo呃，出于某种原因，我以前也做过类似的事情，但curve（Function，-5，5）一直给我一条错误消息。可能在什么地方出错了。但是谢谢你！！！
foo <- function(math_fun, var){

   curve(math_fun, -5, 5)  #plot the mathematical function
   y = math_fun(var)       #compute the function based on a user provided x value
   points(x=var, y=y)      #plot the value from the last step.
}

#A user can use the function defined above in a way as shown below:
Function <- function(x) x^2 + x
foo(Function, var = 2)