IEx - How to cancel multiline command?

Question

When I use IEx and make a typo like additional bracket or ", then most of the time I get a syntax error. But there are cases like this one:

iex(3)> Enum.each '12345', &(IO.puts(&1"))    
...(3)> end   
...(3)> )   
...(3)> '    
...(3)> end    
...(3)> ""    
...(3)> ... ? How to produce syntax error ?    
...(3)>     
BREAK: (a)bort (c)ontinue (p)roc info (i)nfo (l)oaded    
      (v)ersion (k)ill (D)b-tables (d)istribution   

I cannot make a syntax error and continue from scratch and I have to relaunch entire IEx. Is there any keyboard shortcut or command to skip performing current iex(3) and go to next iex(4)?

Answer 1

Start your line with #iex:break

iex(1)> Enum.each '12345', &(IO.puts(&1"))    
...(1)> ...
...(1)> #iex:break

** (TokenMissingError) iex:1: incomplete expression

Answer 2

In general, you can also press Ctrl + G, which will drop you into to the "User switch command" mode with a ---> prompt. From here, you can type i to interrupt your IEx session, then c to reconnect to it; IEx will then state ** (EXIT) interrupted and return to the state it was in immediately before you got stuck. This is a feature of Erlang's shell (erl) that was inherited by IEx.

Example of this in action:

iex(3)> Enum.each '12345', &(IO.puts(&1"))
...(3)> end
...(3)> )
...(3)> '
...(3)> end
...(3)> ""
...(3)>        <-- Ctrl-G goes here (not shown normally)
User switch command
 --> i
 --> c
** (EXIT) interrupted
iex(3)> 

Answer 3

My quick and dirty solution is to produce a syntax error with by spamming """"""""" (which will be interpreted as heredoc).

In your example:

iex(3)> Enum.each '12345', &(IO.puts(&1"))
...(3)> end
...(3)> '
...(3)> end
...(3)> ""
...(3)> """"""""""""""""""""
** (SyntaxError) iex:8: heredoc allows only zero or more whitespace characters followed by a new line after """