How to resolve the algorithm Quine step by step in the Logo programming language
How to resolve the algorithm Quine step by step in the Logo programming language
Table of Contents
Problem Statement
A quine is a self-referential program that can, without any external access, output its own source.
A quine (named after Willard Van Orman Quine) is also known as:
It is named after the philosopher and logician
who studied self-reference and quoting in natural language,
as for example in the paradox "'Yields falsehood when preceded by its quotation' yields falsehood when preceded by its quotation."
"Source" has one of two meanings. It can refer to the text-based program source.
For languages in which program source is represented as a data structure, "source" may refer to the data structure: quines in these languages fall into two categories: programs which print a textual representation of themselves, or expressions which evaluate to a data structure which is equivalent to that expression.
The usual way to code a quine works similarly to this paradox: The program consists of two identical parts, once as plain code and once quoted in some way (for example, as a character string, or a literal data structure). The plain code then accesses the quoted code and prints it out twice, once unquoted and once with the proper quotation marks added. Often, the plain code and the quoted code have to be nested.
Write a program that outputs its own source code in this way. If the language allows it, you may add a variant that accesses the code directly. You are not allowed to read any external files with the source code. The program should also contain some sort of self-reference, so constant expressions which return their own value which some top-level interpreter will print out. Empty programs producing no output are not allowed. There are several difficulties that one runs into when writing a quine, mostly dealing with quoting:
Next to the Quines presented here, many other versions can be found on the Quine page.
Let's start with the solution:
Step by Step solution about How to resolve the algorithm Quine step by step in the Logo programming language
Source code in the logo programming language
make "a [ 116 121 112 101 32 34 124 109 97 107 101 32 34 97 32 91 124 10 102 111 114 101 97 99 104 32 58 97 32 91 32 116 121 112 101 32 119 111 114 100 32 34 124 32 124 32 63 32 93 10 112 114 105 110 116 32 34 124 32 93 124 10 102 111 114 101 97 99 104 32 58 97 32 91 32 116 121 112 101 32 99 104 97 114 32 63 32 93 10 98 121 101 10 ]
type "|make "a [|
foreach :a [ type word "| | ? ]
print "| ]|
foreach :a [ type char ? ]
bye
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