Erlang: “prepending” an element to a tuple

问题

Is it possible to write a faster equivalent to this function?

prepend(X, Tuple) ->
  list_to_tuple([X | tuple_to_list(Tuple)]).

回答1:

As prepending an element is the same as inserting it at position 1, you can use the built-in function erlang:insert_element/3:

> erlang:insert_element(1, {a, b}, z).
{z,a,b}

This function was added in Erlang/OTP R16A.

回答2:

It looks to me like that sort of thing is discouraged. If you want a list, use one.

Getting Started with Erlang:

Tuples have a fixed number of things in them.

回答3:

If you have a finite number of possible tuple lengths, you could do this:

prepend(X, {}) -> {X};
prepend(X, {A}) -> {X, A};
prepend(X, {A, B}) -> {X, A, B};
prepend(X, {A, B, C}) -> {X, A, B, C}.

You can continue this pattern for as long as you need.

来源：https://stackoverflow.com/questions/3936613/erlang-prepending-an-element-to-a-tuple