Simplifying the hash interface; wrap up Poseidon.

Cargo.toml

@@ -26,16 +26,15 @@ log = "0.4.20"
 # optional dependencies
 ark-ff = {version="0.4.0", optional=true}
 ark-ec = {version="0.4.0", optional=true}
-ark-serialize = {version="0.4.2", optional=true}
-ark-crypto-primitives = {version="0.4.0", optional=true}
+ark-serialize = {version="0.4.2", optional=true, features=["std"]}
 curve25519-dalek = {version="4.0.0", optional=true, features=["group"]}
 # anemoi = {git = "https://github.com/anemoi-hash/anemoi-rust", optional=true}
 group = {version="0.13.0", optional=true}
 ark-bls12-381 = {version="0.4.0", optional=true}
 
 [features]
 default = []
-ark = ["dep:ark-ff", "dep:ark-ec", "dep:ark-serialize", "dep:ark-crypto-primitives", "dep:ark-bls12-381"]
+ark = ["dep:ark-ff", "dep:ark-ec", "dep:ark-serialize", "dep:ark-bls12-381"]
 group = ["dep:group", "dep:curve25519-dalek"]
 # anemoi = ["dep:anemoi"]
 

src/hash/index.rs

@@ -0,0 +1,29 @@
+macro_rules! impl_index {
+    ($idx: ty, $struct: ident, $i: tt, Output = $output: ty, Params = [$($type:ident : $trait:ident),*], Constants = $($constgen:ident),*) => {
+        impl<$($type: $trait,)* $(const $constgen: usize,)*> core::ops::Index<$idx> for $struct<$($type,)* $($constgen,)*> {
+            type Output = $output;
+
+            fn index(&self, index: $idx) -> &Self::Output {
+                &self.$i[index]
+            }
+        }
+
+        impl<$($type: $trait,)* $(const $constgen: usize,)*> core::ops::IndexMut<$idx> for $struct<$($type,)* $($constgen,)*> {
+
+            fn index_mut(&mut self, index: $idx) -> &mut Self::Output {
+                &mut self.$i[index]
+            }
+        }
+    };
+}
+
+macro_rules! impl_indexing {
+    ($struct: ident, $field: tt, Output = $output: ty, Params = [$($type:ident : $trait:ident),*], Constants = [$($constgen:ident),*]) => {
+        crate::hash::index::impl_index!(usize, $struct, $field, Output = $output, Params = [$($type : $trait),*], Constants = $($constgen),*);
+        crate::hash::index::impl_index!(core::ops::RangeTo<usize>, $struct, $field, Output = [$output], Params = [$($type : $trait),*], Constants = $($constgen),*);
+        crate::hash::index::impl_index!(core::ops::Range<usize>, $struct, $field, Output = [$output], Params = [$($type : $trait),*], Constants = $($constgen),*);
+        crate::hash::index::impl_index!(core::ops::RangeFrom<usize>, $struct, $field, Output = [$output], Params = [$($type : $trait),*], Constants = $($constgen),*);
+    }
+}
+
+pub(crate) use {impl_index, impl_indexing};