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@breunigs breunigs/pseudo.exs Secret
Created Sep 28, 2017

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Vortrags"folien" zu Pattern Matching
# Assignment
x = 2
[x, y] = [3, 4]
# perl -e '($one, $two) = (1, 2); print $two;'
# ruby -e "one, two = 1, 2; puts two"
# Assignment++
[x, [y, z]] = [5, [6, 7]]
%{hashes: yay} = %{hashes: "yay"}
%{omg: %{what: [are, you]}, doing: %{please: stahp}} = %{omg: %{what: ["are", "you"]}, doing: %{please: "wtf"}}
# Auch für Strings (Character Listen)
"/" <> path = "/nnev/is/awesome"
# Wozu?
## 1. Assert / Guard
true = false
some_fun = fn -> false end
true = some_fun.()
## 2. Offensichtlich: Variablen rausziehen
{status_code, body, headers} = some_http_call()
## 3. Mit Error Handling:
case some_http_call() do
{:ok, some_response} -> IO.puts "yay!"
{:error, some_error} -> IO.puts "oh no!"
_anything_else -> IO.puts ":("
end
## 4. Funktionen (statt if)
defmodule Demo do
def user_data(user, requester )
def user_data(%{id: id}, %{id: id} ), do: "alles über #{id}"
def user_data(%{id: id}, %{permission: :admin}), do: "auch alles über #{id}"
def user_data(%{id: id}, %{id: other_id} ), do: "wenig über #{id}, weil #{other_id} doof ist"
def user_data(_user, _requester ), do: "nein.jpg"
end
# Demo.user_data(%{id: 1}, %{id: 1})
# Demo.user_data(%{id: 1}, %{id: 2})
# Demo.user_data(%{id: 1}, %{id: 2, permission: :admin})
## 4. Funktionen (defaults)
defmodule Demo2 do
def absolutify(url_or_path)
def absolutify("http://" <> _path = url), do: url
def absolutify("/" <> path ), do: "http://nnev.de/#{path}"
end
# Unter der Haube
* Primitive Operationen
* If / Else (bzw. switch)
# Mehr?
https://stackoverflow.com/questions/586362/pattern-matching-implementation
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