blog.kempkens.io/_posts/2014-02-16-joining-a-list-of-binaries-in-erlang.md

layout	title	description	category	tags	image	comments	share
post	Joining a List of Binaries in Erlang	Description and implementation of a function that joins a list of binaries.	posts	erlang programming english	feature credit creditlink header/abstract-3.jpg dargadgetz http://www.dargadgetz.com/ios-7-abstract-wallpaper-pack-for-iphone-5-and-ipod-touch-retina/	true	true

The binary module in Erlang provides an easy way to split binaries using split/2,3, but what if you want to join a list of binaries back together?

There is no built-in function to do this, so I've decided to write my own.

{% highlight erlang linenos %} -spec binary_join([binary()], binary()) -> binary(). binary_join([], _Sep) -> <<>>; binary_join([Part], _Sep) -> Part; binary_join(List, Sep) -> InitAcc = hd(List), lists:foldr(fun (Value, Acc) -> <<Acc/binary, Sep/binary, Value/binary>> end, InitAcc, tl(List)). {% endhighlight %}

It works just like you would expect:

{% highlight erlang %} binary_join([<<"Hello">>, <<"World">>], <<", ">>) % => <<"Hello, World">> binary_join([<<"Hello">>], <<"...">>) % => <<"Hello">> {% endhighlight %}

Hope you find this useful!