add an example to print the Fq and Fr of all the Arkworks' curves (!67)

Cargo.toml

@@ -20,7 +20,33 @@ tracing = "0.1.40"
 tracing-subscriber = "0.3.17"
 
 [dev-dependencies]
+# all the curve dependencies below are used by the `curves` example
+ark-bls12-377 = "0.4.0"
+ark-bls12-381 = "0.4.0"
+ark-bn254 = "0.4.0"
+ark-bw6-761 = "0.4.0"
+ark-cp6-782 = "0.4.0"
+ark-curve25519 = "0.4.0"
+ark-ed-on-bls12-377 = "0.4.0"
+ark-ed-on-bls12-381 = "0.4.0"
+ark-ed-on-bls12-381-bandersnatch = "0.4.0"
+ark-ed-on-bn254 = "0.4.0"
+ark-ed-on-bw6-761 = "0.4.0"
+ark-ed-on-cp6-782 = "0.4.0"
+ark-ed-on-mnt4-298 = "0.4.0"
+ark-ed-on-mnt4-753 = "0.4.0"
+ark-ed25519 = "0.4.0"
+ark-mnt4-298 = "0.4.0"
+ark-mnt4-753 = "0.4.0"
+ark-mnt6-298 = "0.4.0"
+ark-mnt6-753 = "0.4.0"
+ark-pallas = "0.4.0"
 ark-poly-commit = "0.4.0"
+ark-secp256k1 = "0.4.0"
+ark-secp256r1 = "0.4.0"
+ark-secp384r1 = "0.4.0"
+ark-secq256k1 = "0.4.0"
+ark-vesta = "0.4.0"
 criterion = "0.3"
 
 [[bench]]

examples/curves.rs

+//! example usage of this example code
+//! ```shell
+//! cargo run --example curves
+//!     | lines
+//!     | parse "{curve}: {fq} -> {fr}"
+//!     | into int fq fr
+//!     | insert x { (1 - $in.fr / $in.fq) * 100 | math round --precision 1 }
+//! ```
+//!
+//! which gives the followin table
+//!
+//! | curve                            | fq  | fr  | x    |
+//! | -------------------------------- | --- | --- | ---- |
+//! | ark_bls12_377                    | 377 | 253 | 32.9 |
+//! | ark_bls12_381                    | 381 | 255 | 33.1 |
+//! | ark_bn254                        | 254 | 254 | 0    |
+//! | ark_bw6_761                      | 761 | 377 | 50.5 |
+//! | ark_cp6_782                      | 782 | 377 | 51.8 |
+//! | ark_curve25519                   | 255 | 253 | 0.8  |
+//! | ark_ed_on_bls12_377              | 253 | 251 | 0.8  |
+//! | ark_ed_on_bls12_381              | 255 | 252 | 1.2  |
+//! | ark_ed_on_bls12_381_bandersnatch | 255 | 253 | 0.8  |
+//! | ark_ed_on_bn254                  | 254 | 251 | 1.2  |
+//! | ark_ed_on_bw6_761                | 377 | 374 | 0.8  |
+//! | ark_ed_on_cp6_782                | 377 | 374 | 0.8  |
+//! | ark_ed_on_mnt4_298               | 298 | 296 | 0.7  |
+//! | ark_ed_on_mnt4_753               | 753 | 750 | 0.4  |
+//! | ark_ed25519                      | 255 | 253 | 0.8  |
+//! | ark_mnt4_298                     | 298 | 298 | 0    |
+//! | ark_mnt4_753                     | 753 | 753 | 0    |
+//! | ark_mnt6_298                     | 298 | 298 | 0    |
+//! | ark_mnt6_753                     | 753 | 753 | 0    |
+//! | ark_pallas                       | 255 | 255 | 0    |
+//! | ark_secp256k1                    | 256 | 256 | 0    |
+//! | ark_secp256r1                    | 256 | 256 | 0    |
+//! | ark_secp384r1                    | 384 | 384 | 0    |
+//! | ark_secq256k1                    | 256 | 256 | 0    |
+//! | ark_vesta                        | 255 | 255 | 0    |
+use ark_ff::PrimeField;
+
+fn show_curve<Fr: PrimeField, Fq: PrimeField>(name: &str) {
+    println!(
+        "{}: {} -> {}",
+        name,
+        Fq::MODULUS_BIT_SIZE,
+        Fr::MODULUS_BIT_SIZE
+    );
+}
+
+/// takes a sequence of curve crate names and calls the [`show_curve`] function
+/// for you
+///
+/// this macro accepts a trailling comma in case you have a big list that spans
+/// over multiple lines, e.g.
+///
+/// ## examples
+/// ```rust
+/// show_curve(ark_bls12_381)
+/// ```
+/// or
+/// ```rust
+/// show_curve(
+///     ark_bls12_381,
+///     ark_bn254,
+///     ark_pallas,
+///     ark_vesta
+/// )
+/// ```
+/// or
+/// ```rust
+/// show_curve(
+///     ark_bls12_381,
+///     ark_bn254,
+///     ark_pallas,
+///     ark_vesta,
+/// )
+/// ```
+macro_rules! show_curve {
+    ($($c:ident),+ $(,)?) => {
+        $(show_curve::<$c::Fr, $c::Fq>(stringify!($c));)*
+    }
+}
+
+fn main() {
+    show_curve!(
+        ark_bls12_377,
+        ark_bls12_381,
+        ark_bn254,
+        ark_bw6_761,
+        ark_cp6_782,
+        ark_curve25519,
+        ark_ed_on_bls12_377,
+        ark_ed_on_bls12_381,
+        ark_ed_on_bls12_381_bandersnatch,
+        ark_ed_on_bn254,
+        ark_ed_on_bw6_761,
+        ark_ed_on_cp6_782,
+        ark_ed_on_mnt4_298,
+        ark_ed_on_mnt4_753,
+        ark_ed25519,
+        ark_mnt4_298,
+        ark_mnt4_753,
+        ark_mnt6_298,
+        ark_mnt6_753,
+        ark_pallas,
+        ark_secp256k1,
+        ark_secp256r1,
+        ark_secp384r1,
+        ark_secq256k1,
+        ark_vesta,
+    );
+}