Can I disable printing lists of small integers as strings in Erlang shell?

Solution 1:

I don't know if it's possible to change the default behavior of the shell, but you can at least format your output correctly, using io:format.

Here is an example:

1> io:format("~p~n", [[65, 66, 67]]).
"ABC"
ok
2> io:format("~w~n", [[65, 66, 67]]).
[65,66,67]
ok

And since the shell is only for experimenting / maintenance, io:format() should be at least enough for your real application. Maybe you should also consider to write your own format/print method, e.g. formatPerson() or something like that, which formats everything nicely.

Solution 2:

You can disable such behavior with shell:strings/1 function starting with Erlang R16B.

Just remember that this is option global to all node shells, and it might be wise to set it back after finishing playing is shell in longer living nodes.

Solution 3:

I tend to do it by prepending an atom to my list in the shell.

for example:

Eshell V5.7.4  (abort with ^G)
1> [65,66,67].
"ABC"
2> [a|[65,66,67]].
[a,65,66,67]

could also be [a,65,66,67], of course. but [a|fun_that_returns_a_list()] will print "the right thing(ish) most of the time"

Solution 4:

As of Erlang/OTP R16B, you can use the function shell:strings/1 to turn this on or off. Note that it also affects printing of things that are actually meant to be strings, such as "foo" in the following example:

1> {[8,9,10], "foo"}.
{"\b\t\n","foo"}
2> shell:strings(false).
true
3> {[8,9,10], "foo"}.   
{[8,9,10],[102,111,111]}