Problem matchin map with ^key

Questions / Help
,
1

I’m studying some tutorial about elixir

but I have a problem finding the solution in this example

nola = %{ name: "New Orleans", founded: 1718 }
field = "founded"
%{^field: city_founded} = nola
** (SyntaxError) iex:14: syntax error before: field


#I try with atom
field = :founded
%{^field: city_founded} = nola
** (SyntaxError) iex:15: syntax error before: field

#with Charlist
field = 'founded'
%{^field: city_founded} = nola 
** (SyntaxError) iex:16: syntax error before: field

In the manual it show that this is correct, but it didn’t work in my IEx 1.6.5 (compiled with OTP 19)

2

You can not pin an atom key. You need to use => syntax:

iex(1)> nola = %{name: "Foo"}
%{name: "Foo"}
iex(2)> field = :name
:name
iex(3)> %{^field => name} = nola
%{name: "Foo"}
iex(4)> name
"Foo"
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