qwtel/test.md

## test.md

      
    Raw
  

              test.md
            
          
    Data serialization formats

Comparison of selected data serialization formats.

JSON - ECMA-404
EDN - github.com/edn-format/edn
CLJ - clojure.org/reader

Whitespace


JSON
EDN
CLJ


whitespace character
U+0009 (tab) U+000A (newline) U+000D (return) and U+0020 (space)
⚠️ specs does not specify
whitespace chars, explicitly mentions just ,


delimiters
whitespaces, all structural ({ } : , [ ]) and literal (true false null) tokens
whitespaces and [ ] { } ( ) ( ⚠️ additional delimiters not mentioned in specs " \ ;)
[ ] { } ( ) " \ ; @ ^ ` ~ (:warning: no explicit mention in specs)


Null


JSON
EDN
CLJ


null literal
null
nil
nil


Booleans


JSON
EDN
CLJ


true literal
true
true
true


false literal
false
false
false


Characters


JSON
EDN
CLJ


syntax
NONE ❌
\X
\X


special characters
n/a
\newline \tab \return \space
\newline \tab \return \space \backspace \formfeed


unicode escapes
n/a
\uNNNN
\uNNNN


octal escapes
n/a
NO ❌
\o0 to \o377


Strings


JSON
EDN
CLJ


syntax
wrapped in "
wrapped in "
wrapped in "


may span multiple lines
NO ❌
YES
YES


characters which must be escaped
" \ and control characters (U+0000 to U+001F)
" \
" \


escape characters
\" \\ \/ \b \f \n \r \t
\" \\ \n \r \t
\" \\ \' \b \f \n \r \t


unicode escapes
\uNNNN
NO, not mentioned in specs ❌
\uNNNN


octal escapes
NO ❌
NO ❌
\0 to \377


Integers


JSON
EDN
CLJ


varbitrary precision indicator
NO ❌
N suffix
N suffix


vvalid signs
-
- +
- +


-0 is valid
YES
YES
YES


decimal integer
YES
YES
YES


custom radix
NO ❌
NO ❌
NNrNNNNN


hexa integer
NO ❌
NO ❌
0xNNNNN, but undocumented ⚠️


octal integer
NO ❌
NO ❌
0NNN, but undocumented ⚠️


Non-integral numbers


JSON
EDN
CLJ


ratios
NO ❌
NO ❌
NN/NN


decimals
NO ❌
M suffix
M suffix


floats
YES
YES
YES


valid signs
-
- +
- +


Identifiers


JSON
EDN
CLJ


symbols
NO ❌
YES
YES


symbol start character
n/a
alphabetic, + - . followed by non-numeric symbol character, * ! _ ? $ % & = < > (/ is special, see below)
alphabetic, + - * ! _ ? (/ and . are special, see below), ( ⚠️ specs does not mention $ = < > % &)


symbol character
n/a
alphanumeric, + - . * ! _ ? $ % & = < > : #
alphanumeric,  + - * ! _ ? (. / and : are special, see below), ( ⚠️ specs does not mention $ = < > % & # ')


special symbol character
n/a
/, used alone or in following combinations foo/bar (:warning: In my opinion specs does not allow foo// combination, see this ticket). First character after slash must follow rule for symbol start character
/, used alone or in following combinations foo/bar foo// (:warning: latter combination is undocumented). ., used as prefix or suffix is reserved to Clojure, used inside symbol divides namespace or package names. : can be used inside symbol, used as suffix is reserved to Clojure (currently it produces an error). (:warning: undocumented restrictions: symbol can not contain ::, namespace part can not end with :,  first character after slash must follow rule for symbol start character)


keyword
NO ❌
prefixed with :
prefixed with :


keyword character
n/a
alphanumeric, + - . * ! _ ? $ % & = < > : #
alphanumeric,  + - * ! _ ? (. / and : are special, see below), ( ⚠️ specs does not mention $ = < > % & # ')


keyword invalid second character
n/a
:
none special


special keyword character
n/a
/, used in following combinations :foo// :foo/bar. First character after slash must follow rule for symbol start character
/, used in following combinations :foo/bar :foo// (:warning: latter combination is undocumented). : used as second character resolves keyword in the current namespace, used as suffix is reserved to Clojure (currently it produces an error). (:warning: undocumented restrictions: keyword can not contain :: other than as a prefix, namespace part can not end with :,  first character after slash must follow rule for symbol start character) Specs also say that keywords cannot contain '.' ( ⚠️ restriction meant probably only for the name part of the keyword) or name classes.


Collections


JSON
EDN
CLJ


list
NO ❌
(a b c)
(a b c)


vector
[a, b, c]
[a b c]
[a b c]


set
NO ❌
#{a b c} items are unique
#{a b c} items are unique


map
{string1 : val1, string2 : val2]
{key1 val1 key2 val2} keys are unique
{key1 val1 key2 val2} keys are unique


Special


JSON
EDN
CLJ


comments
NO ❌
; till the end of the line
; till the end of the line


discard
NO ❌
#_ discards next read object
#_ discards next read object


tagged literal
NO ❌
# followed immediately by a symbol starting with an alphabetic character
# followed immediately by a symbol starting with an alphabetic character


builtin tags
n/a
#inst #uuid
#inst #uuid, deftypes, defrecords and java classes constructors


regular expressions
NO ❌
NO ❌
#"pattern"


macros
NO ❌
NO ❌
' (quote), @ (deref), ^ (metadata), #' (var quote), #(% %n %&) (anonymous function), ` (syntax quote), ~ (unquote), ~@ (unquote splicing). (:warning: undocumented macros #= #! #< and deprecated #^)
	JSON	EDN	CLJ
whitespace character	U+0009 (tab) U+000A (newline) U+000D (return) and U+0020 (space)	⚠️ specs does not specify	whitespace chars, explicitly mentions just `,`
delimiters	whitespaces, all structural (`{` `}` `:` `,` `[` `]`) and literal (`true` `false` `null`) tokens	whitespaces and `[` `]` `{` `}` `(` `)` ( ⚠️ additional delimiters not mentioned in specs `"` `\` `;`)	`[` `]` `{` `}` `(` `)` `"` `\` `;` `@` `^` ` `~` (:warning: no explicit mention in specs)
	JSON	EDN	CLJ
true literal	`true`	`true`	`true`
false literal	`false`	`false`	`false`
	JSON	EDN	CLJ
syntax	NONE ❌	`\X`	`\X`
special characters	n/a	`\newline` `\tab` `\return` `\space`	`\newline` `\tab` `\return` `\space` `\backspace` `\formfeed`
unicode escapes	n/a	`\uNNNN`	`\uNNNN`
octal escapes	n/a	NO ❌	`\o0` to `\o377`
	JSON	EDN	CLJ
syntax	wrapped in `"`	wrapped in `"`	wrapped in `"`
may span multiple lines	NO ❌	YES	YES
characters which must be escaped	`"` `\` and control characters (U+0000 to U+001F)	`"` `\`	`"` `\`
escape characters	`\"` `\\` `\/` `\b` `\f` `\n` `\r` `\t`	`\"` `\\` `\n` `\r` `\t`	`\"` `\\` `\'` `\b` `\f` `\n` `\r` `\t`
unicode escapes	`\uNNNN`	NO, not mentioned in specs ❌	`\uNNNN`
octal escapes	NO ❌	NO ❌	`\0` to `\377`
	JSON	EDN	CLJ
varbitrary precision indicator	NO ❌	`N` suffix	`N` suffix
vvalid signs	`-`	`-` `+`	`-` `+`
`-0` is valid	YES	YES	YES
decimal integer	YES	YES	YES
custom radix	NO ❌	NO ❌	`NNrNNNNN`
hexa integer	NO ❌	NO ❌	`0xNNNNN`, but undocumented ⚠️
octal integer	NO ❌	NO ❌	`0NNN`, but undocumented ⚠️
	JSON	EDN	CLJ
ratios	NO ❌	NO ❌	`NN/NN`
decimals	NO ❌	`M` suffix	`M` suffix
floats	YES	YES	YES
valid signs	`-`	`-` `+`	`-` `+`
	JSON	EDN	CLJ
symbols	NO ❌	YES	YES
symbol start character	n/a	alphabetic, `+` `-` `.` followed by non-numeric symbol character, `*` `!` `_` `?` `$` `%` `&` `=` `<` `>` (`/` is special, see below)	alphabetic, `+` `-` `*` `!` `_` `?` (`/` and `.` are special, see below), ( ⚠️ specs does not mention `$` `=` `<` `>` `%` `&`)
symbol character	n/a	alphanumeric, `+` `-` `.` `*` `!` `_` `?` `$` `%` `&` `=` `<` `>` `:` `#`	alphanumeric, `+` `-` `*` `!` `_` `?` (`.` `/` and `:` are special, see below), ( ⚠️ specs does not mention `$` `=` `<` `>` `%` `&` `#` `'`)
special symbol character	n/a	`/`, used alone or in following combinations `foo/bar` (:warning: In my opinion specs does not allow `foo//` combination, see this ticket). First character after slash must follow rule for symbol start character	`/`, used alone or in following combinations `foo/bar` `foo//` (:warning: latter combination is undocumented). `.`, used as prefix or suffix is reserved to Clojure, used inside symbol divides namespace or package names. `:` can be used inside symbol, used as suffix is reserved to Clojure (currently it produces an error). (:warning: undocumented restrictions: symbol can not contain `::`, namespace part can not end with `:`, first character after slash must follow rule for symbol start character)
keyword	NO ❌	prefixed with `:`	prefixed with `:`
keyword character	n/a	alphanumeric, `+` `-` `.` `*` `!` `_` `?` `$` `%` `&` `=` `<` `>` `:` `#`	alphanumeric, `+` `-` `*` `!` `_` `?` (`.` `/` and `:` are special, see below), ( ⚠️ specs does not mention `$` `=` `<` `>` `%` `&` `#` `'`)
keyword invalid second character	n/a	`:`	none special
special keyword character	n/a	`/`, used in following combinations `:foo//` `:foo/bar`. First character after slash must follow rule for symbol start character	`/`, used in following combinations `:foo/bar` `:foo//` (:warning: latter combination is undocumented). `:` used as second character resolves keyword in the current namespace, used as suffix is reserved to Clojure (currently it produces an error). (:warning: undocumented restrictions: keyword can not contain `::` other than as a prefix, namespace part can not end with `:`, first character after slash must follow rule for symbol start character) Specs also say that keywords cannot contain '.' ( ⚠️ restriction meant probably only for the name part of the keyword) or name classes.
	JSON	EDN	CLJ
list	NO ❌	`(a b c)`	`(a b c)`
vector	`[a, b, c]`	`[a b c]`	`[a b c]`
set	NO ❌	`#{a b c}` items are unique	`#{a b c}` items are unique
map	`{string1 : val1, string2 : val2]`	`{key1 val1 key2 val2}` keys are unique	`{key1 val1 key2 val2}` keys are unique
	JSON	EDN	CLJ
comments	NO ❌	`;` till the end of the line	`;` till the end of the line
discard	NO ❌	`#_` discards next read object	`#_` discards next read object
tagged literal	NO ❌	`#` followed immediately by a symbol starting with an alphabetic character	`#` followed immediately by a symbol starting with an alphabetic character
builtin tags	n/a	`#inst` `#uuid`	`#inst` `#uuid`, deftypes, defrecords and java classes constructors
regular expressions	NO ❌	NO ❌	`#"pattern"`
macros	NO ❌	NO ❌	`'` (quote), `@` (deref), `^` (metadata), `#'` (var quote), `#(% %n %&)` (anonymous function), ` (syntax quote), `~` (unquote), `~@` (unquote splicing). (:warning: undocumented macros `#=` `#!` `#<` and deprecated `#^`)