[WIP] Proposal to establish burn::baselib::... collecting pre-tensor common libs; starting with indexing.

[crutcher]

This is incomplete; it is a proposal to establish a burn::baselib::... tree; which exists pre-core and pre-tensor; but is also public for third-parties to use.

the first candidate is lifting the indexing, shape, range, and slice utils.

i've not resolved how to re-export things to maintain backwards compat; this is a rough proof of concept.

[crutcher]

@laggui based upon discussions in development > #general

[codecov]

Codecov Report

❌ Patch coverage is 76.47059% with 32 lines in your changes missing coverage. Please review.
✅ Project coverage is 63.53%. Comparing base (26c1e47) to head (35efa3b).
⚠️ Report is 118 commits behind head on main.

Files with missing lines	Patch %	Lines
...rates/burn-common/src/baselib/indexing/as_index.rs	30.00%	21 Missing ⚠️
crates/burn-common/src/baselib/indexing/shape.rs	87.91%	11 Missing ⚠️

❌ Your patch check has failed because the patch coverage (76.47%) is below the target coverage (80.00%). You can increase the patch coverage or adjust the target coverage.
❌ Your project check has failed because the head coverage (63.53%) is below the target coverage (80.00%). You can increase the head coverage or adjust the target coverage.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #3432   +/-   ##
=======================================
  Coverage   63.52%   63.53%           
=======================================
  Files         982      984    +2     
  Lines      109937   109937           
=======================================
+ Hits        69838    69847    +9     
+ Misses      40099    40090    -9     

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[antimora]

We might want to review other common shape operations implemented in Candle for potential reuse or inspiration: candle-core/src/shape.rs

Candle’s shape.rs includes utilities like:

• Shape validation and broadcasting helpers.
• Indexing/slicing logic with bounds checks.
• Contiguous shape transformations (e.g., reshape, permute, expand).
• Stride and contiguous memory layout calculations.
• Compact methods for computing element count and dimensionality.

[crutcher]

I have a bunch of indexing / traversal iterator util stuff from a java tensor impl I built; and some of it might be worth stealing:
https://github.com/crutcher/tapestry/tree/main/src/main/java/org/tensortapestry/zspace/indexing

Basically, we often need these things not just to write correct third-party code that has the same generic flexibility as the API; but to write implementations/bindings of array-like objects into the tensor implementation layers.

[github-actions]

This PR has been marked as stale because it has not been updated for over a month