[Python-ideas] Is there any idea about dictionary destructing?

[Nikolas Vanderhoof]

And this should print:

'some data'
1
2
3

On Sat, Apr 7, 2018 at 4:16 PM, Nikolas Vanderhoof <
nikolasrvanderhoof at gmail.com> wrote:

> This would be a very handy feature, but Coconut (which is just python with
> some extra functional-style features) also has support for this kind of
> pattern-matching:
> http://coconut-lang.org
>
>
> ​Since Coconut will compile to Python (2 or 3) you can just write in
> Coconut and use the resulting code in your Python.
>
> Using your first example in coconut would be nearly identical, except I
> believe the entire dictionary must be specified (I am not sure about this).
>
> data = {
>     'direct': 'some data',
>     'nested': {
>         'lst_data': [1, 2, 3],
>         'int_data': 1
>     }
> }
>
> {
>     'direct': direct,
>     'nested': {
>         'lst_data': [a, b, c],
>         'int_data': _
>     }
> } = data
>
> print(direct)
> print(a)
> print(b)
> print(c)
>
>
> And this should print:
>
> On Sat, Apr 7, 2018 at 1:26 PM, thautwarm <yaoxiansamma at gmail.com> wrote:
>
>> We know that Python support the destructing of iterable objects.
>>
>> m_iter = (_ for _ in range(10))
>> a, *b, c = m_iter
>>
>> That's pretty cool! It's really convenient when there're many corner
>> cases to handle with iterable collections.
>> However destructing in Python could be more convenient if we support
>> dictionary destructing.
>>
>> In my opinion, dictionary destructing is not difficult to implement and
>> makes the syntax more expressive. A typical example is data access on
>> nested data structures(just like JSON), destructing a dictionary makes
>> the logic quite clear:
>>
>> data = {
>>     "direct": "some data",
>>     "nested": {
>>         "lst_data": [1, 2, 3],
>>         "int_data": 1
>>     }
>> }
>> {
>>    "direct": direct,
>>     "nested": {
>>         "lst_data": [a, b, c],
>>     }
>> } = data
>>
>>
>> Dictionary destructing might not be very well-known but it really helps.
>> The operations on nested key-value collections are very frequent, and the
>> codes for business logic are not readable enough until now. Moreover Python
>> is now popular in data processing which must be enhanced by the entire
>> support of data destructing.
>>
>> Here are some implementations of other languages:
>> Elixir, which is also a popular dynamic language nowadays.
>>
>> iex> %{} = %{:a => 1, 2 => :b}
>> %{2 => :b, :a => 1}
>> iex> %{:a => a} = %{:a => 1, 2 => :b}
>> %{2 => :b, :a => 1}
>> iex> a
>> 1
>> iex> %{:c => c} = %{:a => 1, 2 => :b}
>> ** (MatchError) no match of right hand side value: %{2 => :b, :a => 1}
>>
>> And in F#, there is something similar to dictionary destructing(actually,
>> this destructs `struct` instead)
>> type MyRecord = { Name: string; ID: int } let IsMatchByName record1
>> (name: string) = match record1 with | { MyRecord.Name = nameFound;
>> MyRecord.ID = _; } when nameFound = name -> true | _ -> false let
>> recordX = { Name = "Parker"; ID = 10 } let isMatched1 = IsMatchByName
>> recordX "Parker" let isMatched2 = IsMatchByName recordX "Hartono"
>>
>> All of them partially destructs(or matches) a dictionary.
>>
>> thautwarm
>>
>>
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>>
>
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