How to resolve the algorithm Short-circuit evaluation step by step in the Quackery programming language

Published on 12 May 2024 09:40 PM

How to resolve the algorithm Short-circuit evaluation step by step in the Quackery programming language

Table of Contents

Problem Statement

Assume functions   a   and   b   return boolean values,   and further, the execution of function   b   takes considerable resources without side effects, and is to be minimized. If we needed to compute the conjunction   (and): Then it would be best to not compute the value of   b()   if the value of   a()   is computed as   false,   as the value of   x   can then only ever be   false. Similarly, if we needed to compute the disjunction (or): Then it would be best to not compute the value of   b()   if the value of   a()   is computed as   true,   as the value of   y   can then only ever be   true. Some languages will stop further computation of boolean equations as soon as the result is known, so-called   short-circuit evaluation   of boolean expressions

Create two functions named   a   and   b,   that take and return the same boolean value. The functions should also print their name whenever they are called. Calculate and assign the values of the following equations to a variable in such a way that function   b   is only called when necessary: If the language does not have short-circuit evaluation, this might be achieved with nested     if     statements.

Let's start with the solution:

Step by Step solution about How to resolve the algorithm Short-circuit evaluation step by step in the Quackery programming language

Source code in the quackery programming language

  [ say "evaluating "
    ]this[ echo cr ]       is ident    (     -->   )

  [ iff say "true"
    else say "false" ]     is echobool (   b -->   )

  [ swap iff drop done
    times drop
    false ]done[ ]         is SC-and   ( b n -->   )

  [ swap not iff drop done
    times drop
    true ]done[ ]          is SC-or    ( b n -->   )

  [ ident
    2 times not ]          is a        (   b --> b )

  [ ident
    4 times not ]          is b        (   b --> b )

  [ say "i = "
    dup echobool
    say " AND j = "
    dup echobool
    cr
    [ a 1 SC-and b ]
    say "result is "
    echobool cr cr ]       is AND-demo (     -->   )

  [ say "i = "
    dup echobool
    say " OR j = "
    dup echobool
    cr
    [ a 1 SC-or b ]
    say "result is "
    echobool
    cr cr ]                is OR-demo  (     -->   )

  true  true  AND-demo
  true  false AND-demo
  false true  AND-demo
  false false AND-demo
  cr
  true  true  OR-demo
  true  false OR-demo
  false true  OR-demo
  false false OR-demo

  

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