Data-E in JSON

From Erights

This is a definition of JSON syntax for Data-E.

It was created around 2009-01-07 due to interest in using CapTP in Cajita systems, with a JSON syntax for the message/serialization layer.

Except for literals and that it uses tuples with string tags instead of TermL tagged terms, it is exactly the same as the Data-E in TermL format as implemented by deASTKit.

It is being implemented as part of User:Kevin Reid's GSoC project, caja-captp.

Contents 1 Atoms 2 Literals (old design) 3 Import and ibid 4 Call 5 Define 6 See also

Atoms

The atom types are String and float64, which are copied as-is into the JSON structure. Integers are not atoms and must be handled by an uncaller, since JavaScript-based JSON implementations will not preserve int/float distinctions or the values of integers that don't fit in float64. Characters are not atoms and must be handled by an uncaller.

	Data-E Source	JSON
String	"foo"	"foo"
Float64	-9.99	-9.99

Literals (old design)

XXX Delete/fold this into the previous section. See [1] for the context.

String literals are copied as-is into JSON (rationale: compactness, readability). Characters are tagged since JSON does not have character values. Integers are tagged and written as strings since JavaScript-based JSON implementations will not preserve the values of integers that don't fit in float64.

XXX justify or remove tagging of float64.

XXX review what base/format to write integers in. In particular, if there is such, it should be readily convertible to a the format used by some big-integer-in-JavaScript library.

	Data-E Source	JSON	Notes
String	"foo"	"foo"
Integer	9	["int", "9"]	The numeric string shall be only digits, with no leading zeros. XXX Decide about negative integers
Float64	9.99	["float64", 9.99]
Character	'f'	["char", "f"]	The string shall be of length 1. XXX Consider UTF-16 issues.

Import and ibid

Data-E Source	JSON
foo	["import", "foo"]
t_9	["ibid", 9]

Call

Data-E Source	JSON
foo.bar(baz...)	["call", foo, "bar", [baz...]]

Define

Data-E Source	JSON
def t_9 := bar	["define", 9, bar]
def t_9 := ...t_9...	["defrec", 9, ...["ibid", 9]...]

See also

• CapTP on HTTP