Add From<i{int}> for signed integer conversion for Fields

[mmaker]

Signed integer conversion is already integrated in the source code definition for Fp but it's not exposed from the trait

[Pratyush]

Looks like a good idea to me; does this passes local tests?

[mmaker]

looks like?

maker@forbici ff % cargo test
warning: some crates are on edition 2021 which defaults to `resolver = "2"`, but virtual workspaces default to `resolver = "1"`
note: to keep the current resolver, specify `workspace.resolver = "1"` in the workspace root's manifest
note: to use the edition 2021 resolver, specify `workspace.resolver = "2"` in the workspace root's manifest
    Finished test [optimized + debuginfo] target(s) in 0.14s
     Running unittests src/lib.rs (/Users/maker/Code/arkworks/algebra/target/debug/deps/ark_ff-829d73734feaaeeb)

running 21 tests
test biginteger::arithmetic::test_find_relaxed_naf_usefulness ... ok
test biginteger::tests::test_biginteger64 ... ok
test biginteger::tests::test_biginteger128 ... ok
test biginteger::tests::test_biginteger256 ... ok
test biginteger::tests::test_biginteger448 ... ok
test biginteger::tests::test_biginteger384 ... ok
test biginteger::tests::test_biginteger768 ... ok
test biginteger::tests::test_biginteger832 ... ok
test const_helpers::tests::test_mul_buffer_correctness ... ok
test biginteger::arithmetic::test_find_relaxed_naf_correctness ... ok
test fields::models::cubic_extension::cube_ext_tests::test_from_base_prime_field_element ... ok
test fields::models::cubic_extension::cube_ext_tests::test_from_base_prime_field_elements ... ok
test fields::models::cubic_extension::cube_ext_tests::test_norm_for_towers ... ok
test fields::models::fp12_2over3over2::test::test_characteristic_square_mod_6_is_one ... ok
test fields::models::fp::montgomery_backend::test::test_mont_macro_correctness ... ok
test fields::models::quadratic_extension::quad_ext_tests::test_from_base_prime_field_element ... ok
test fields::models::quadratic_extension::quad_ext_tests::test_from_base_prime_field_elements ... ok
test fields::no_std_tests::test_from_into_biguint ... ok
test const_helpers::tests::test_mul_buffer_soundness - should panic ... ok
test fields::no_std_tests::test_batch_inversion ... ok
test fields::no_std_tests::test_from_be_bytes_mod_order ... ok

test result: ok. 21 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.01s

   Doc-tests ark-ff

running 39 tests
test ff/src/biginteger/mod.rs - biginteger::BigInteger::is_zero (line 905) ... ok
test ff/src/biginteger/mod.rs - biginteger::BigInteger::div2 (line 841) ... ok
test ff/src/biginteger/mod.rs - biginteger::BigInteger::from_bits_le (line 959) ... ok
test ff/src/biginteger/mod.rs - biginteger::BigInteger::get_bit (line 932) ... ok
test ff/src/biginteger/mod.rs - biginteger::BigInteger::add_with_carry (line 749) ... ok
test ff/src/biginteger/mod.rs - biginteger::BigInteger::divn (line 863) ... ok
test ff/src/biginteger/mod.rs - biginteger::BigInt (line 77) ... ok
test ff/src/biginteger/mod.rs - biginteger::BigInteger::is_odd (line 883) ... ok
test ff/src/biginteger/mod.rs - biginteger::BigInteger::from_bits_be (line 945) ... ok
test ff/src/biginteger/mod.rs - biginteger::BigInteger::is_even (line 894) ... ok
test ff/src/biginteger/mod.rs - biginteger::BigInteger::mul2 (line 791) ... ok
test ff/src/biginteger/mod.rs - biginteger::BigInteger::muln (line 816) ... ok
test ff/src/biginteger/mod.rs - biginteger::BigInteger::num_bits (line 915) ... ok
test ff/src/biginteger/mod.rs - biginteger::BigInteger::to_bits_le (line 990) ... ok
test ff/src/biginteger/mod.rs - biginteger::BigInteger::sub_with_borrow (line 771) ... ok
test ff/src/biginteger/mod.rs - biginteger::BigInteger::to_bits_be (line 973) ... ok
test ff/src/biginteger/mod.rs - biginteger::BigInteger::to_bytes_be (line 1007) ... ok
test ff/src/biginteger/mod.rs - biginteger::BigInteger::to_bytes_le (line 1022) ... ok
test ff/src/const_helpers.rs - const_helpers::const_for (line 8) ... ok
test ff/src/biginteger/mod.rs - biginteger::signed_mod_reduction (line 687) ... ok
test ff/src/fields/field_hashers/mod.rs - fields::field_hashers::DefaultFieldHasher (line 30) ... ok
test ff/src/fields/mod.rs - fields::Field (line 117) ... ok
test ff/src/fields/models/cubic_extension.rs - fields::models::cubic_extension::CubicExtField<P>::new (line 103) ... ok
test ff/src/fields/models/fp/montgomery_backend.rs - fields::models::fp::montgomery_backend::MontFp (line 576) ... ok
test ff/src/fields/mod.rs - fields::Field::from_base_prime_field (line 230) ... ok
test ff/src/fields/mod.rs - fields::Field (line 142) ... ok
test ff/src/fields/models/quadratic_extension.rs - fields::models::quadratic_extension::QuadExtField<P>::new (line 119) ... ok
test ff/src/fields/models/fp2.rs - fields::models::fp2::Fp2<P>::mul_assign_by_fp (line 105) ... ok
test ff/src/fields/sqrt.rs - fields::sqrt::LegendreSymbol (line 4) ... ok
test ff/src/fields/models/fp3.rs - fields::models::fp3::Fp3<P>::mul_assign_by_fp (line 78) ... ok
test ff/src/fields/models/quadratic_extension.rs - fields::models::quadratic_extension::QuadExtField<P>::norm (line 144) ... ok
test ff/src/fields/prime.rs - fields::prime::PrimeField (line 8) ... ok
test ff/src/fields/sqrt.rs - fields::sqrt::LegendreSymbol::is_qnr (line 38) ... ok
test ff/src/fields/sqrt.rs - fields::sqrt::LegendreSymbol::is_qr (line 49) ... ok
test ff/src/fields/sqrt.rs - fields::sqrt::LegendreSymbol::is_zero (line 23) ... ok
test ff/src/lib.rs - (line 60) ... ok
test ff/src/lib.rs - (line 135) ... ok
test ff/src/lib.rs - (line 162) ... ok
test ff/src/lib.rs - (line 96) ... ok

test result: ok. 39 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 10.18s
maker@forbici ff % git status
On branch master
Your branch is ahead of 'origin/master' by 1 commit.
  (use "git push" to publish your local commits)

nothing to commit, working tree clean
maker@forbici ff % git push mmaker
Everything up-to-date

[Pratyush]

Sounds good! I think we might not have tests for this functionality, so if you could add those then we can merge ASAP. Thanks!

[mmaker]

we don't have them for unsigned integers either, do we?

[mmaker]

(just so that I can add them too)

[Pratyush]

We don't I think. If you could add those in this PR that would be great, otherwise I can do it in a follow-up PR.

[mmaker]

added