Transform function with multiple nested expression functions using '_.'

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Gabriell Constantin Vig

• January 21, 2020 13:03

I as a user would like to use multiple functions which accept '_.' as the iterating value nested.

 

Currently you cannot for example use a filter with a nested map function, as the '_.' in the filter function will overwrite the '_.' in the map function.

Therefore I would like the option to use an alias for each nested function, or some other solution which gives the desired outcome.

An example using suggested alias method to iterate over a nested list:

["map", "alias_a",
    ["map", "alias_b",
        ["eq", "foo", "alias_b.key"],
    "alias_a.inner_list"],
"nested_list"]

 

This would make it easier to write DTL because we would not have to define a rule for each nested expression which uses the '_.' operator.

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• Official comment

  

  Geir Ove Grønmo

  • October 13, 2020 10:57

  Do you have a real-world example where such a feature would be required?

  We have considered adding a "let" function earlier, but have not done so yet as it is unclear if it is necessary or if it introduces too much complexity.

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