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Chapter 9  EXDR Data Interchange Format



We have defined a data interchange format called EXDR for the communication between ECLiPSe and other languages. The data types available in this format are integer, double, string, list, nil, structure and anonymous variable. This is intended to be the subset of ECLiPSe types that has a meaningful mapping to many other languages' data types. The mapping onto different languages is given in the following table. For details of the mapping between Java classes/interfaces and EXDR/ECLiPSe types see Section 8.3.1.
EXDR type ECLiPSe type TCL type Java type
Integer integer int java.lang.Integer
e.g. 123 123 123
Long integer string java.lang.Long
e.g. 5000000000 5000000000 5000000000
Double float double java.lang.Double/Float
e.g. 12.3 12.3 12.3
String string string java.lang.String
e.g. "abc" abc "abc"
List ./2 list java.util.Collection
e.g. [a,b,c] {a b c}
Nil [ ]/0 empty string java.util.Collection
e.g. [ ] {} ""  
Struct compound list CompoundTerm/Atom
e.g. foo(bar,3) {foo bar 3}  
Variable variable string null
e.g. _ _
The EXDR Integer data type is a 32-bit signed integer, the EXDR Long data type is a 64-bit signed integer, bigger ECLiPSe integers cannot be represented. The EXDR Variable type only allows singleton, anonymous variables, which means that it is not possible to construct a term where a variable occurs in several places simultaneously. The main use of these variables is as placeholders for result arguments in remote procedure calls.


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