I am working on a format consisting of serialized B-tree. It is essentially a dictionary, but serialized. This means you can traverse the structure and perform zero-copy lookups without parsing: https://github.com/fastserial/lite3

This is a `map`, which bears semblence with a Json object. The following might look like an incorrect paylood, but will actually parse as valid EDN:

  {:a 1, "foo" :bar, [1 2 3] four}
  // Note that keys and values can be elements of any type. 
  // The use of commas above is optional, as they are parsed as whitespace.

Some projects in Haskell use Aterms, as it is suitable for exchanging Sum and Product types.

I think ASN.1 (and ASN.1X which is I added a few additional types such as key/value list and TRON string) is better. (I also made up a text-based ASN.1 format called TER which is intended to be converted to the binary DER format. It is also intended that extensions and subsets of TER can be made for specific applications if needed.) (I also wrote a DER decoder/encoder library in C, and programs that use that library, to convert TER to DER and to convert JSON to DER.)

ASN.1 (and ASN.1X) has many similar types than EDN, and a comparison can be made:

- Null (called "nil" in EDN) and booleans are available in ASN.1.

- Strings in ASN.1 are fortunately not limited to Unicode; you can also use ISO 2022, as well as octet strings and bit strings. However, there is no "single character" type.

- ASN.1 does have a Enumerated type, although the enumeration is made as numbers rather than as names. The EDN "keywords" type seems to be intended for enumerations.

- The integer and floating point types in ASN.1 are already arbitrary precision. If a reader requires a limited precision (e.g. 64-bits), it is easy to detect if it is out of range and result in an error condition.

- ASN.1 does not have a separate "list" and "vector" type, but does have a "set" type and a "sequence" type. A key/value list ("map") type is a nonstandard type in ASN.1X, but standard ASN.1 does not have a key/value list type.

- ASN.1 does have tagging, although its working is difference from EDN. ASN.1 does already have a date/time type though, so this extension is not needed. Extensions are possible by application types and private types, as well as by other methods such as External, Embedded PDV, and the nonstandard

- The rational number type (in edn.c but the main EDN specification does not seems to mention it), is not a standard type in ASN.1 but ASN.1X does have such a type.

(Some people complain that ASN.1 is complicated; this is not wrong, but you will only need to implement the parts that you will use (which is simpler when using DER rather than BER; I think BER is not very good and DER is much better), which ends up making it simpler while also capable of doing the things that would be desirable.)

(But, EDN does solve some of the problems with JSON, such as comments and a proper integer type.)