Announcing Chapel 1.21.0!

[Brad C. <bra...@hp...>]

Dear Chapel community --

Cray, a Hewlett Packard Enterprise Company, and the Chapel open-source
community are proud to announce the release of Chapel version 1.21!

[Mac users: the Homebrew formula is still working its way through the
system... see https://github.com/Homebrew/homebrew-core/pull/52790 ]

This is the first of two releases that we will be making this month.
Chapel 1.21 is our typical semi-annual release containing numerous
feature and performance improvements.  Chapel 1.22 will focus on
changing Chapel's implicitly indexed types to 0-based indexing from
Chapel's historical choice of 1-based.  We recommend that users with
existing Chapel code incrementally upgrade to version 1.21 before 1.22
in order to ease the transition.

Chapel 1.21 includes the following highlights, many of which support
our goal of stabilizing Chapel's core features for a forthcoming
Chapel 2.0 release:

* Chapel's modules and namespaces have improved in a number of ways,
   including:

   - the addition of a new `import` statement that provides a more
     precise way of referring to a module's contents

   - a new ability to rename modules when they're used via `as` (e.g.,
     `use MyLongModuleName as M;`)

   - prototypical support for storing a module's sub-modules in their
     own files

   - reduced bleeding of symbols between modules by making `use`
     private by default and leveraging it in Chapel-provided modules

* Chapel strings are now validated to ensure that they are UTF8, and
   the `bytes` type has been improved to be a true peer to strings.

* Chapel now supports split initialization of variables, constants,
   types, params, and refs, which permits the declaration of a symbol
   to occur in a distinct statement from its initialization.

* We added several features that support a more index-neutral style of
   programming, such as support for looping over heterogeneous tuples
   and a `.indices` query for most collection types.

* This release also contains several new performance improvements and
   optimizations including:

   - better performance and scalability when creating distributed
     domains and arrays

   - improvements to the unordered operation optimization and its
     associated `unorderedCopy()` routine

   - optimized `on`-statement performance for InfiniBand networks

   - improved performance (and correctness) of mis-aligned `ugni` data
     transfers

* The language specification has been converted from PDF to HTML to
   better integrate it with Chapel's other online documentation (see
   https://chapel-lang.org/docs/language/spec/index.html)

* The `ofi`/libfabric implementation of the runtime has improved in
   terms of functionality, portability, and performance.

In addition, Chapel 1.21 contains many other feature enhancements, bug
fixes, and documentation improvements.  For a far more complete list
of changes, including pointers to supporting documentation, please
refer to CHANGES.md within the release or online:

   https://github.com/chapel-lang/chapel/blob/release/1.21/CHANGES.md

To download and install the release, see:

   https://chapel-lang.org/download.html

And for a list of everyone who contributed to Chapel 1.21, please see:

   https://github.com/chapel-lang/chapel/blob/release/1.21/CONTRIBUTORS.md

As always, we're interested in feedback on how we can make the Chapel
language, implementation, libraries, and tools more useful to you.

On behalf of the Chapel project,
-Brad Chamberlain


------------------------------------
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