Invoking maps & arrays: allow sequences?

[ChristianGruen]

Invoking maps & arrays: allow sequences?

[michaelhkay]

[ 3, 4, 5 ](2, 1)

Did you mean that, or did you mean

[ 3, 4, 5 ]((2, 1))

Do you want it to be a variadic function with a variable number of arguments, or a function that takes an integer sequence as a single argument?

[ChristianGruen]

Glad you ask this question; it was mine as well:

• From the non-expert user perspective (not knowing the fundamental details between lookups and function calls), the variadic variant would be more intuitive, ideally with a flattened result over the result of all arguments.
• From the implementor perspective, a single argument would be easier to realize – and it would be less invasive, as it would allow us to introduce additional parameters in the future.

[michaelhkay]

In general we made a decision in principle that functions should not do implicit mapping over their arguments. You can argue that map:get($map, $key) should do implicit mapping if $key is a sequence of keys, but you can equally argue that it should do implicit mapping if $map is a sequence of maps. So I suggest we don't do this.

As for $map($key) if we allow $key to be a sequence here then we have to revise the complex rules for the implicit type of the map as a function and therefore the subsumption rules for map types, which is a swamp I would rather not revisit.

[ChristianGruen]

Thanks for your assessment. I assume that only a minority of users would benefit from this, so I’d be happy to close it.

[ndw]

The CG agreed to close this issue without action at meeting 065