In short, context is an alternative stack. Contrary to values on the normal, everyday perl stack, that come and go as subroutines are being called, context is retained within a lambda. Predicates use context instead of the perl stack to receive their parameters. In the following code 

context $a, $b, $c;
predicate1 {
predicate2 {
}}

[download]
Both predicate1 and predicate2 use values $a, $b, $c from the context, even though predicate2 is called after code that called predicate1 is finished. That code is identical to the following: 

context $a, $b, $c;
predicate1 {
context $a, $b, $c;
predicate2 {
}}

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From the architectural point of view, context is syntactic sugar. The same effects can be achieved without using it, but at the price of more complex and/or ugly code.

In reply to Re^4: IO::Lambda: call for participation by dk
in thread IO::Lambda: call for participation by dk

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