mps.baseLanguageExtensions: New language with extensions to BaseLanguage

[alamqadem]

This language adds a series of extension to BaseLanguage.
The extensions are described in the following table:

Name	Extension	Description
elvis operation	maybeNullStr ?: "fallback"
integer sequence	[0..n]
zip operation	s1.zip(s2)
group by operation	s1.groupBy({~it => // select key;})
select with index	s.selectIdx({~it, int index => ...})
where with index	s.whereIdx({~it, int index => ...})
forEach with index	s.forEachIdx({~it, int index => ...})

Elvis operation

When handling nullable values and you want to prevent NullPointerExceptions and have a "safe fallback value" of sorts, you can use the Elvis Operation to achieve a semantic similar to the ternary operation expression that will select and return your fallback, should the nullable value actually be null.

null ?: "fallback" -> result: "fallback"
"valid" ?: "fallback" -> "valid"
"valid" ?: null -> "valid"
null ?: null -> null

The operation will also be able to widen the typing to a common supertype, in case the fallback isn't immediately a subtype of the left hand side.

Integer sequence

[0 .. n] would produce a sequence of integers containing all integers from 0 to n.
These are the 3 types of integer sequences that are supported:

• [0..n] finite with a fixed upper limit;
• [0..#e] finite with an expression as an upper limit;
• [0..] infinite syntax.

Zip operation

The operation s1.zip(s2) creates a sequence of tuples, given a tuple of sequences.
The sequence is stopped as soon as one of the sequences is consumed.

Group by operation

When operating on sequences and you want to identify groups of elements that match the same criteria, or more specifically that return the same element when a certain "bucket-sorting-function" is applied, then groupBy is the correct way. This adds an eagerly evaluated operation on sequences that produces a map, where the keys are the "buckets" identified by the provided function and the values are sequences of elements in the original sequence that returned the respective key. All elements from the original sequence will have a single representation in the resulting map.

Select, where, forEach with index

These operation allow to access the current index when applying the operation select, where or forEach.
These operations are lazy.

[sergej-koscejev]

Can/should this language be integrated with com.mbeddr.mpsutil.blutil, located in the blutil folder?

[sergej-koscejev]

Also, the 2022.3 MPS version is quite old, are you prepared to handle cascading merges up to master?

[alexanderpann]

I didn't take a look at the implementation, but please don't forget the data flow aspect for the new concepts.

[arimer]

Is there a schedule for when this feature should be ready? @dalbrecht1 , @alamqadem

[dalbrecht1]

Is there a schedule for when this feature should be ready? @dalbrecht1 , @alamqadem

I realized that I would need a few things that I only have access to downstream to make that pretty (so I will probably contribute some more than initially planned), as well as there are some housekeeping things still open to do on that branch. On top other responsibilities were more important. I'll see what I can do in the next days. But I'd really want to target prior to end of year to get this off my plate.