Try to add S-Expressions (LISP family)

Cargo.toml

@@ -26,11 +26,15 @@ serde-transcode = "1.1.1"
 # Should tend to be equal to the official list of data formats supported by serde: https://serde.rs/#data-formats
 #bson = "2.3"
 #ciborium = "0.2"
+#envy = "0.4" # No `Deserializer` exposed.
+#envy-store = "0.1" # No `Deserializer` exposed.
 serde_json = "1.0"
 json5 = "0.4"
+#serde-lexpr = "0.1"
 serde-pickle = "1.0"
 serde_qs = "0.10"
 rmp-serde = "1.1"
 ron = "0.8"
 #toml = "0.5"
 serde_yaml = "0.9"
+ 

src/lib.rs

@@ -27,6 +27,7 @@ pub enum Input {
     //Cbor,
     Json,
     Json5,
+    //SExpression,
     Pickle,
     //Qs,   // NOTE: The crate is not noted "(serialization only)" on the [serde listing](https://serde.rs/#data-formats) but it does not expose a `Deserializer`
     //Rmp,  // NOTE: It appears that we are forced to deserialize into a concrete type
@@ -41,6 +42,7 @@ pub enum Output {
     //Cbor,
     Json,
     //Json5,    // NOTE: The crate is not noted "(deserialization only)" on the [serde listing](https://serde.rs/#data-formats) but it does not expose a `Serializer`
+    //SExpression,
     Pickle,
     Qs,
     Rmp,
@@ -72,8 +74,8 @@ fn de(opt: &Opt, input: &mut dyn Read, output: &mut dyn Write) {
         Input::Bson => {
             use bson::Deserializer;
 
-            let mut deserializer = bson::from_reader(input).unwrap(); // FIXME: need which type annotation?
-            ser(opt, &mut deserializer, output);
+            let deserializer = bson::from_reader(input).unwrap();    // FIXME: can we skip the type annotation?
+            ser(opt, deserializer, output);
         }
         */
         Input::Json => {
@@ -93,6 +95,14 @@ fn de(opt: &Opt, input: &mut dyn Read, output: &mut dyn Write) {
             let mut deserializer = Deserializer::from_str(&buf).unwrap();
             ser(opt, &mut deserializer, output);
         }
+        /*
+        Input::SExpression => {
+            use serde_lexpr as Deserializer;
+
+            let deserializer = Deserializer::from_reader(input).unwrap();    // FIXME: can we skip the type annotation?
+            ser(opt, deserializer, output);
+        }
+        */
         Input::Pickle => {
             use serde_pickle::Deserializer;
 
@@ -156,6 +166,14 @@ where
             // NOTE: serde_json’s PrettyFormatter and CompactFormatter are incompatibles…
             // serde_transcode::transcode(deserializer, serializer).unwrap();
         }
+        /*
+        Output::SExpression => {
+            use serde_lexpr::to_writer as Serializer;
+
+            let serializer = Serializer::new(output);    // FIXME: There is a `to_writer` but the Serializer is not exposed directly.
+            serde_transcode::transcode(deserializer, serializer).unwrap();
+        }
+        */
         Output::Pickle => {
             use serde_pickle::Serializer;