CSCI 2041 Lab14: Review

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                            LAB 14 QUESTIONS
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The following are review problems which


Review Problem 1: Exponentiation in Calculon
============================================

  Consider extending Calculon to include exponentiation associated with
  the `^' symbol. Below are some examples of the desired behavior.
  ,----
  | calculon> 2^5;
  | - : IntDat(32)
  | 
  | calculon> 2^4;
  | - : IntDat(16)
  | 
  | calculon> 2^2 + 2^5 - 2^4;
  | - : IntDat(20)
  | 
  | calculon> 16 / 8;
  | - : IntDat(2)
  | 
  | calculon> (4^2) / (2^3);
  | - : IntDat(2)
  | 
  | calculon> 4^2 / 2^3;
  | - : IntDat(2)
  | 
  | calculon> 2^2^2;
  | - : IntDat(16)
  | 
  | calculon> 2^2^3^4;
  | - : IntDat(16777216)
  `----

  - Exponentiation has higher precedence than other operators so must be
    parsed before addition, subtraction, multiplication, and division.
  - As shown, exponentiation can be repeated in a chain like `2^2^2'.

  Discuss which parts of Calculon's system would need to be altered to
  support this new operator. Be specific about which files and functions
  would need to change. If you are feeling adventurous, copy your A5
  files to a new directory and code the change.


Review Problem 2: Lexing and Streams
====================================

  Examine Calculon's main lexing function called `lex_string'.  Recall
  that this function processes an entire string and transforms it into a
  list of tokens. Consider how it might be converted to a *stream*
  instead of a list. Discuss how this might work with the interface for
  streams provided in OCamls standard library `Stream' module.

  - Discuss how the state of the stream can be represented
  - Discuss changes that would need to take place in the code to make it
    compatible with the `Stream' module

  Below is the desired behavior via a `lex_stream' function which
  creates a stream of tokens.

  ,----
  | # let stream = Calclex.lex_stream "let x = 4*2 in x-6;";;
  | val stream : Calclex.token Stream.t = <abstr>
  | 
  | # Stream.next stream;;
  | - : Calclex.token = Calclex.Let
  | # Stream.next stream;;
  | - : Calclex.token = Calclex.Ident "x"
  | # Stream.next stream;;
  | - : Calclex.token = Calclex.Equal
  | # Stream.next stream;;
  | - : Calclex.token = Calclex.IntTok 4
  | # Stream.next stream;;
  | - : Calclex.token = Calclex.Times
  | # Stream.next stream;;
  | - : Calclex.token = Calclex.IntTok 2
  | # Stream.next stream;;
  | - : Calclex.token = Calclex.In
  | # Stream.next stream;;
  | - : Calclex.token = Calclex.Ident "x"
  | # Stream.next stream;;
  | - : Calclex.token = Calclex.Minus
  | # Stream.next stream;;
  | - : Calclex.token = Calclex.IntTok 6
  | # Stream.next stream;;
  | - : Calclex.token = Calclex.Semicolon
  | 
  | # Stream.peek stream;;
  | - : Calclex.token option = None
  | # Stream.next stream;;
  | Exception: Stdlib.Stream.Failure.
  `----