mathlib

83092fb4 - feat(data/matrix/notation): add `!![1, 2; 3, 4]` notation (#14991)

feat(data/matrix/notation): add `!![1, 2; 3, 4]` notation (#14991) This adds `!![1, 2; 3, 4]` as a matlab-like shorthand for `matrix.of ![![1, 2], ![3, 4]]`. This has special support for empty arrays, where `!![,,,]` is a matrix with 0 rows and 3 columns, and `![;;;]` is a matrix with 3 rows and zero columns.