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    Enticement snippet (Ten15 was a capability architecture and operating system with graphical user interface):

    Flex was usually programmed in Algol-68 (Ian Currie was on one of the Algol-68 committees - I’m not sure of the details), with the extension that procedures could (safely) escape from their scope - in modern language, this meant that functions were first-class values - indeed, in Flex the result of a program could be a function! Not the text for a function, or even the binary implementing the function, but a capability to the function closure value, complete with bindings to all the variables in its non-local scope.