impl Display for BlockHash and TxId

Cargo.lock

@@ -190,6 +190,11 @@ dependencies = [
  "rand 0.4.2 (registry+https://github.com/rust-lang/crates.io-index)",
 ]
 
+[[package]]
+name = "hex"
+version = "0.3.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+
 [[package]]
 name = "hex-literal"
 version = "0.1.1"
@@ -435,6 +440,7 @@ dependencies = [
  "blake2-rfc 0.2.18 (git+https://github.com/gtank/blake2-rfc?rev=7a5b5fc99ae483a0043db7547fb79a6fa44b88a9)",
  "byteorder 1.2.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "ff 0.4.0",
+ "hex 0.3.2 (registry+https://github.com/rust-lang/crates.io-index)",
  "lazy_static 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)",
  "pairing 0.14.2",
  "rand 0.4.2 (registry+https://github.com/rust-lang/crates.io-index)",
@@ -493,6 +499,7 @@ dependencies = [
 "checksum futures-cpupool 0.1.8 (registry+https://github.com/rust-lang/crates.io-index)" = "ab90cde24b3319636588d0c35fe03b1333857621051837ed769faefb4c2162e4"
 "checksum gcc 0.3.54 (registry+https://github.com/rust-lang/crates.io-index)" = "5e33ec290da0d127825013597dbdfc28bee4964690c7ce1166cbc2a7bd08b1bb"
 "checksum generic-array 0.9.0 (registry+https://github.com/rust-lang/crates.io-index)" = "ef25c5683767570c2bbd7deba372926a55eaae9982d7726ee2a1050239d45b9d"
+"checksum hex 0.3.2 (registry+https://github.com/rust-lang/crates.io-index)" = "805026a5d0141ffc30abb3be3173848ad46a1b1664fe632428479619a3644d77"
 "checksum hex-literal 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)" = "4da5f0e01bd8a71a224a4eedecaacfcabda388dbb7a80faf04d3514287572d95"
 "checksum hex-literal-impl 0.1.1 (registry+https://github.com/rust-lang/crates.io-index)" = "1d340b6514f232f6db1bd16db65302a5278a04fef9ce867cb932e7e5fa21130a"
 "checksum lazy_static 1.0.0 (registry+https://github.com/rust-lang/crates.io-index)" = "c8f31047daa365f19be14b47c29df4f7c3b581832407daabe6ae77397619237d"

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);