Coming from Erlang I’m used to variables being imutable, Elixir doesn’t provide this same level of comfort that I am used to. For instance, when learning Erlang we are taught that once a variable is bound it cannot be changed.

1> A = "Looking good so far!".
"Looking good so far!"
2> A.
"Looking good so far!"
3> A = "Even better?".
** exception error: no match of right hand side value "Even better?"

In Elixir the story is not quite the same…

iex(1)> a = "Looking good so far!"
"Looking good so far!"
iex(2)> a
"Looking good so far!"
iex(3)> a = "Even better?"
"Even better?"

Normally this probably isn’t a big deal, I guess, maybe… but it really starts to suck is when you were hoping to get that sweet, sweet patern matching. To force the variable in Elixir to not pick up a new value you have to put a caret in front of the variable.

iex(1)> a = "Looking good so far!"
"Looking good so far!"
iex(2)> a
"Looking good so far!"
iex(3)> ^a = "Even better?"
** (MatchError) no match of right hand side value: "Even better?"

I’m not sure of what would be a better solution; however, I am not a fan of this in the language.