Lec10 - CMPSC 461 Programming Language Concepts Lecture 10...

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CMPSC 461: Programming Language Concepts Lecture 10 Instructor: Prof. Swarat Chaudhuri
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Data abstraction Procedure / list empty-env extend-env apply-env Implementation Interface Client Client Environment +
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Recursive data types Bintree ::= Number | Symbol Bintree Bintree | Symbol Bintree Environment: - contains? - traverse-postorder - traverse-preorder -
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Defining interfaces: follow the grammar Data type defined recursively using grammar What we need A way to construct an instance of the type according to a rule. (Constructor) Given a data item, answer: “was this item constructed using rule X?” (Predicate) If it was, a way to break it down into sub-items following rule X. (Extractor) Why? Because clients need these operations to follow the grammar. Each rule gives a variant of the data type.
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Recursive data types Bintree ::= leaf: Number | int-2: Symbol Bintree Bintree | int-1: Symbol Bintree leaf int-2 int-1
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define-datatype A mechanism in our Scheme dialect to define
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This note was uploaded on 09/30/2008 for the course CMPSC 461 taught by Professor Chaudhuri during the Fall '08 term at Penn State.

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Lec10 - CMPSC 461 Programming Language Concepts Lecture 10...

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