Revision plans for v4.0

[akabe]

We plan to the following changes in the next major version up.

Backward incompatible changes

• Low-level internal representation of flags. (The flags are defined as polymorphic variant in ver 3 or below, but will be implemented as char because BLAS/LAPACK's flags are characters. Overhead of conversion from polymorphic variant into char will be removed.)
  • The type of parameters ?up (for symmetric or triangular matrices) is bool in ver 3, [< A | L | U ] Slap.Common.uplo` in ver 4.
  • The type of parameters ?diag (for unit or non-unit triangular matrices) is [ N | U ] in ver 3, Slap.Common.diag in ver 4.
  • The type of parameter uplo of lacpy is [ L | U ] option in ver 3, [< A | L | U ] Slap.Common.uplo` in ver 4.
• Changing subtyping tricks by phantom types. (The current version uses a subtyping trick for flags, vectors, matrices described at our paper, but polymorphic variant can achieve subtyping more simply. We will adopt the latter.)
  • The types of flags in Slap.Common, and 'cnt_or_dsc parameters of vectors and matrices will be changed.
• Simplification of type parameters of Slap.Common.trans. ((('m, 'n, 'cnt_or_dsc) mat -> ('n, 'm, 'cnt_or_dsc) mat) trans is too long since it has extra type parameter 'cnt_or_dsc. (m * 'n -> 'n * 'm) trans is much simpler.)
  • The type of transpose flags in Slap.Common and parameters ~trans will be changed.
• Deprecation of several functions.
  • Slap.Size.pred_dyn |-> Slap.Size.pred
  • Slap.Size.fold_left |-> Slap.Size.iter_acc
  • etc.

Backward compatible changes

Perhaps some changes will be contained in ver 4.1 or above.

• Removing extra dynamic checks.
  • BLAS/LAPACK functions will be slightly faster.
  • -noassert option will be supported by the configure script.
• Introduction of generative existential types by GADTs.
  • More lightweight syntax can be used.
• Dynamic checks of equalility/inequality of type-level sizes.
  • E.g., if_eq : 'n Size.t -> 'm Size.t -> (('n, 'm) eq -> 'a) -> (unit -> 'a) -> 'a
• More utility functions: cons, hd, tl, etc.
• More LAPACK functions: laswp, lapmt, gtsv
• Sized array module.