RFC: Reference Version Constraints in paket.template

Problem

In paket.template files I can reference the currently build version (via CURRENTVERSION) and the package's resolved version from paket.lock (via LOCKEDVERSION). I'd like to reference the complete version constraint from paket.dependencies (e.g. via VERSIONCONSTRAINT) as well.

When using type project templates, the version constraints from paket.dependencies are used per default, CURRENTVERSION is controlled via interproject-references and LOCKEDVERSION via lock-dependencies. For type file I see no way to access the original version constraint from paket.depenencies, though.

Proposal

Introduce VERSIONCONSTRAINT as a placeholder for the complete version constraint from paket.dendencies, including the optional "-group" suffix like in LOCKEDVERSION.

Example:

dependencies
   FSharp.Core VERSIONCONSTRAINT   # equivalent to VERSIONCONSTRAINT-Main

Known Workaround

Right now one has to duplicate the version constraint, either by manually copying it or by reconstructing using the existing placeholders, e.g. ~> LOCKED:Minor .
Especially for complex constraints, this is a hassle.

Start by tracing how placeholders in paket.template are parsed and resolved against paket.dependencies and paket.lock, with attention to type file templates and the optional group suffix used by LOCKEDVERSION. Done means VERSIONCONSTRAINT expands to the complete original constraint, including its group suffix, and supports the example dependency declaration.