leanprover / leanprover/lean4

`UIntX.pow` and `IntX.pow` needs native implementaton

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#7,887 3 comments 0 reactions 0 assignees View on GitHub

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Description

#7886 introduces UIntX.pow functions which are just the naive implementation, so we can provide a Pow UIntX Nat instance. (Similarly for signed fixed-width integers.) #7893 introduces BitVec.pow.

These functions need a native implementation provided by @[extern]. This is likely non-trivial as it will probably require extending Lean's bignum library with a version of mpz_powm.

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Research direction

Start by reviewing the UIntX.pow work from #7886 and the BitVec.pow work from #7893, then trace the existing bignum library and @[extern] integrations. Compare the needed behavior with GMP's mpz_powm documentation. Done means native implementations support UIntX.pow and IntX.pow rather than the naive versions, with the relevant behavior verified.

Written by the indexing model from the issue text.

Assessment

Domain
compilers
Issue type
Feature
Difficulty
5/5
Estimated time
Over a week
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
25/100

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