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FinalPattern

The Identifier is the defining occurence of a variable name, and the eExpr is the ValueGuard-expression. When matched against a specimen, a FinalPattern defines the variable to have as its value the specimen as coerced by the ValueGuard. A variable declared by a FinalPattern may not be assigned to, and programs that contain such an assignment must be statically rejected. XXX The current E implementations only rejects such assignments dynamically, not statically.

BNF:	Noun ":" eExpr
XML DTD:	<!ELEMENT finalPattern (Noun, %eExpr;)>
Java:	A variable defined by a FinalPattern is always simple. The guard ":any" has a statically known meaning, since "any" is an unshadowable name bound in the universal scope. Given that "T" below is statically determined to be a particular Java class, and using "foo" for all other ValueGuard expressions, we have the following cases: x :any final Object x = specimen; x :T final T x = E.as(specimen, T.class, optEjector); x :foo final Object x = E.call(foo, "coerce", specimen, optEjector);
Example:	def a :foo := b
in Kernel-E:	same
in XML:	<defineExpr> <finalPattern> <Noun>a</Noun> <Noun>foo</Noun> </finalPattern> <Noun>b</Noun> </defineExpr>
in Java:	final Object a = E.call(foo, "coerce", b, null);