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Extraction of elements of tuples

开发者 https://www.devze.com 2023-02-06 22:08 出处:网络
Given one list with one tuple: [{4,1,144}] How to extract the first element of the tuple insi开发者_JAVA技巧de the list:

Given one list with one tuple:

[{4,1,144}]

How to extract the first element of the tuple insi开发者_JAVA技巧de the list:

element(1,lists:nth(1,L))

Do you have a simpler solution?


Try this:

1> A = [{3,1,1444}].
[{3,1,1444}]
2> [{X, _, _}] = A.
[{3,1,1444}]
3> X.
3
4> 


Given that you get exactly what you state, a list with one tuple, even easier would be (using element/2)

element(1, hd(L)).

A pattern matching variant like shk suggested is probably even nicer, depending on the context.


you could also consider using records syntax if you want some semantics embedded into your tuples

-record(x, {y, z}).

1> A = #x{y=b, z=c}.
2> A#x.y.
b

all records are in fact tuples and you dont have to worry about order of elements in that tuple nor about adding/removing elements.

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