问题
Apart from the fact that =:= prevents unwanted integer casts:
1> 1=:=1.0.
false
What is the advantage of using =:= with terms in general?
Better performance?
回答1:
The biggest advantage of =:= is it returns true only for same terms in the same way as pattern matching. So you can be sure they are same. 1 and 1 are same terms and 1 with 1.0 are not. That's it. If you write function like foo(A, B) when A =:= B -> A. and bar(A, B) when A =:= B -> B. they will behave same. If you use == it will not be same functions. It simply prevents surprise. For example, if you make some key/value storage it would not be right if you store value with key 1 and then get this value if ask for key 1.0. And yes, there is a little bit performance penalty with == but least astonishment is far more important. Just use =:= and =/= when it is your intent to compare same terms. Use == and /= only if it is your intent to compare numbers.
回答2:
*Eshell V5.9.3.1 (abort with ^G)
1> 1.0==1.
true
2> 1.0=:=1.
false
When we go with == it will transfer both elements into the same format to match.
With =:= it does not happen – when the two elements are same-type and same-value it will return true.
来源：https://stackoverflow.com/questions/9790815/what-is-the-difference-between-and-in-erlang-when-used-with-terms-in-gene