impl Display for BlockHash and TxId

zcash_primitives/Cargo.toml

@@ -8,6 +8,7 @@ authors = [
 [dependencies]
 byteorder = "1"
 ff = { path = "../ff" }
+hex = "0.3"
 lazy_static = "1"
 pairing = { path = "../pairing" }
 rand = "0.4"

zcash_primitives/src/block.rs

@@ -1,8 +1,18 @@
+use hex;
+use std::fmt;
 use std::ops::Deref;
 
 #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
 pub struct BlockHash(pub [u8; 32]);
 
+impl fmt::Display for BlockHash {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut data = self.0.to_vec();
+        data.reverse();
+        formatter.write_str(&hex::encode(data))
+    }
+}
+
 /// A Zcash block header.
 pub struct BlockHeader(BlockHeaderData);
 

zcash_primitives/src/lib.rs

@@ -4,6 +4,7 @@ extern crate lazy_static;
 extern crate blake2_rfc;
 extern crate byteorder;
 extern crate ff;
+extern crate hex;
 extern crate pairing;
 extern crate rand;
 extern crate sapling_crypto;

zcash_primitives/src/transaction/mod.rs

@@ -1,5 +1,7 @@
 use byteorder::{LittleEndian, ReadBytesExt, WriteBytesExt};
+use hex;
 use sapling_crypto::redjubjub::Signature;
+use std::fmt;
 use std::io::{self, Read, Write};
 use std::ops::Deref;
 
@@ -23,6 +25,14 @@ const SAPLING_TX_VERSION: u32 = 4;
 #[derive(Clone, Copy, Debug, PartialEq, Eq, Hash)]
 pub struct TxId(pub [u8; 32]);
 
+impl fmt::Display for TxId {
+    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
+        let mut data = self.0.to_vec();
+        data.reverse();
+        formatter.write_str(&hex::encode(data))
+    }
+}
+
 /// A Zcash transaction.
 #[derive(Debug)]
 pub struct Transaction(TransactionData);