New array declaration syntax

Developers
41

Thanks! We definitely want to hear from end users on topics like this.

1 Like
42

I like array[N] matrix[I, J] more otherwise, but as @Bob_Carpenter said, it would be inconsistent with declaring an array of reals etc. Moreover, I think array is neither a keyword in Stan or a reserved keyword, so wouldnā€™t this change potentially break some old code? So I voted for matrix[I, J][N]. For the type specifiers in function arguments I would like to have

  • matrix[] if matrix[I, J][N] is the variable declaration
  • array[] matrix if array[N] matrix[I, J] is the variable declaration
1 Like
43

I think we would have array declarations be consistent across all types, I was just using matrix as an example, sorry I should have been clear about that when I made the poll.

Good point about making array a reserved keyword. Iā€™m not sure how big of an issue thatā€™ll be. (It should be possible to not make it a reserved keyword but weā€™d probably have to mangle the parser a bit.)

4 Likes
44

Finally got around to reading the whole thread - why didnā€™t the 2nd poll have `matrix[N][I, J] either? haha, oh well.

I guess OCaml does this, though itā€™s got to have the most backwards (literally) version Iā€™ve seen - the type int option list is a list of options of ints, like [Some 1, None, Some 2]. But it does seem to be expressive enough for them so far.