Question

请允许我帮助我了解一下这里的经历。

lists:dropwhile(fun(X) -> X < 8 end, lists:seq(1,10)).

"	
" % ??? what is this ? why not [8,9,10]

lists:dropwhile(fun(X) -> X < 7 end, lists:seq(1,10)).  

[7,8,9,10] % this is correct

Answer 1

Your results are actually correct in both cases. The unexpected string in the first case is due to the fact that in Erlang strings are just lists of integers. Therefore, Erlang chooses to interpret your first list as a string, since it contains only printable ASCII codes. In the second case the list contains the code 7, which is not printable, so Erlang is forced to interpret it as an integer list.

You can always print the actual integer list by using

MyList = lists:dropwhile(fun(X) -> X < 8 end, lists:seq(1,10)),
io:format("~w", [MyList]).

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