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VarPattern

The Identifier is the defining occurence of a variable name, and the eExpr is the SlotGuard-expression. In Kernel-E (our only concern here), the SlotGuard-expression may only be "settable" or "settable(ValueGuardExpr)". (All other cases are transformed away by deslotification.) When matched against a specimen, a VarPattern defines the variable to have as its value the specimen as coerced by the ValueGuard. Likewise, when such a variable is assigned to, the new value of the variable is the rValue as coerced by the ValueGuard. 

BNF:
 
"var" Noun ":" eExpr
 
XML DTD:
 
<!ELEMENT varPattern (Noun, %eExpr;)>

Java:

By scope analysis, explained elsewhere (XXX), the variable is determined to either be simple or boxed.

Simple 
var x :settable
 
Object x = specimen;
 
var x :settable(T)
 
T x = E.as(specimen,
           T.class,
           optEjector);
 
var x :settable(foo)
 
Object x = E.call(foo,
                  "coerce",
                  specimen,
                  optEjector);
Boxed 
var x :settable
 
final Object[] x__Box = { specimen };
 
var x :settable(T)
 
final T[] x__Box = {
    E.as(specimen,
         T.class,
         optEjector)
};
 
var x :settable(foo)
 
final Object[] x__Box = {
    E.call(foo,
           "coerce",
           specimen,
           optEjector);
};

 

 
Example:
 to be written 
in Kernel-E:
 to be written 
in XML:
 to be written 
in Java:
 to be written

 

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Unless stated otherwise, all text on this page which is either unattributed or by Mark S. Miller is hereby placed in the public domain.
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