COMPSCI 61A Lecture 27: CS61A-Lecture 10-31-2016
4 Nov 2016
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Homework party wednesday 11/02 6:30-8:30pm in 247 cory. Bonus point for submitting a complete project by wednesday 11/16 @ 11:59pm. Maps composition revisions due sunday 11/06 @ 11:59pm. New midterm recovery policy: students who scored below 45/90 on midterm 1 & midterm 2 to combined can earn back exam points by attending discussion. Symbols are bound to values in the current environment. All other legal expressions are represented as scheme lists, called combinations. Cond expression: (cond ( ) () (else )) The value of an if expression is the value of a sub-expression. Evaluation procedure: evaluate the predicate, choose a sub-expression, evaluate that sub-expression in place of the whole expression. The quote special form evaluates to the quoted expression, which is not evaluated. The itself is the value of the expression. The scheme_read parser converts shorthand to a regular old combination that starts with the word quote . A frame represents an environment by having a parent frame.
