ITEC 380 2009fall ibarland

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lect13c
project notes; python cont.

• Mention:

  (define 2nd (compose first rest)) (eval '(+ (* 3 4) 5))

• Mention: assoc and/or java.util.Map<IdExpr,ValExpr>.
• Mention: When parsing, we don't know the bindings at all; only when eval hits an exact eval'ing,
• Test suite: The test harness I gave you just calls eval with one arg. You can
  • Modify the test harness;
  • have eval as a wrapper to real-eval, though this means re-writing most of your (recursive) calls to eval;
  • Make a version of eval which can take either one or two args:

    (define eval (case-lambda [(expr) …] [(expr env) …]))

• Add this to N2 sol'n OO vs procedural: An organizational difference: rows vs columns in the table of variants vs. methods.
  When adding new variants to Expr which one reminds you to update the new methods? (What's the dual point to this complaint? Is it as important?)
  (Remember that inheritance (and its associated polymorphism) is the key non-syntactic-sugar difference between the two.)
• Continue lect13b-python—python primer
• Btw, you can also check out a ruby tutorial if you are interested. It borrows some things from scripting language like python (simple overloading/conversions between strings, arrays, maps, etc) and some explicit scheme/lisp conventions (variable names ending in '?' or '!' for predicates and mutators).

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©2009, Ian Barland, Radford University Last modified 2009.Dec.04 (Fri)

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