revert printing of characters

Cargo.lock

@@ -51,6 +51,18 @@ version = "1.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "cf1de2fe8c75bc145a2f577add951f8134889b4795d47466a54a5c846d691693"
 
+[[package]]
+name = "blake2"
+version = "0.8.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "94cb07b0da6a73955f8fb85d24c466778e70cda767a568229b104f0264089330"
+dependencies = [
+ "byte-tools",
+ "crypto-mac",
+ "digest",
+ "opaque-debug",
+]
+
 [[package]]
 name = "blake2b_simd"
 version = "0.5.10"
@@ -174,6 +186,16 @@ dependencies = [
  "winapi 0.3.8",
 ]
 
+[[package]]
+name = "crypto-mac"
+version = "0.7.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "4434400df11d95d556bac068ddfedd482915eb18fe8bea89bc80b6e4b1c179e5"
+dependencies = [
+ "generic-array",
+ "subtle",
+]
+
 [[package]]
 name = "digest"
 version = "0.8.1"
@@ -323,6 +345,12 @@ dependencies = [
  "wasm-bindgen",
 ]
 
+[[package]]
+name = "keccak"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "67c21572b4949434e4fc1e1978b99c5f77064153c59d998bf13ecd96fb5ecba7"
+
 [[package]]
 name = "kernel32-sys"
 version = "0.2.2"
@@ -742,6 +770,7 @@ checksum = "d29ab0c6d3fc0ee92fe66e2d99f700eab17a8d57d1c1d3b748380fb20baa78cd"
 name = "scryer-prolog"
 version = "0.8.123"
 dependencies = [
+ "blake2",
  "cpu-time",
  "crossterm",
  "dirs",
@@ -761,6 +790,7 @@ dependencies = [
  "ripemd160",
  "rug",
  "rustyline",
+ "sha3",
  "unicode_reader",
 ]
 
@@ -779,6 +809,19 @@ version = "0.7.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "388a1df253eca08550bef6c72392cfe7c30914bf41df5269b68cbd6ff8f570a3"
 
+[[package]]
+name = "sha3"
+version = "0.8.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "dd26bc0e7a2e3a7c959bc494caf58b72ee0c71d67704e9520f736ca7e4853ecf"
+dependencies = [
+ "block-buffer",
+ "byte-tools",
+ "digest",
+ "keccak",
+ "opaque-debug",
+]
+
 [[package]]
 name = "signal-hook"
 version = "0.1.13"
@@ -833,6 +876,12 @@ version = "0.3.4"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "7f3eb36b47e512f8f1c9e3d10c2c1965bc992bd9cdb024fa581e2194501c83d3"
 
+[[package]]
+name = "subtle"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2d67a5a62ba6e01cb2192ff309324cb4875d0c451d55fe2319433abe7a05a8ee"
+
 [[package]]
 name = "syn"
 version = "1.0.18"

src/prolog/heap_print.rs

@@ -160,7 +160,7 @@ fn char_to_string(is_quoted: bool, c: char) -> String {
         '\u{d8}' ..= '\u{f6}' => c.to_string(),
         '\u{f8}' ..= '\u{74f}' => c.to_string(),
         '\x20' ..= '\x7e' => c.to_string(),
-        _ => format!("\\{:x}\\", c as u32),
+        _ => format!("\\x{:x}\\", c as u32),
     }
 }