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Structure.md

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Structure

This file outlines the basic structure of the relision library.

termfactory

The termfactory module contains the TermFactory struct that can create terms. In order for this to work, the factory has to know ^ROOT, which is special.

The basic literals are:

  • integers
  • floating point numbers
  • strings
  • symbols
  • bit strings
  • Booleans

The TermFactory instance does not know anything about default types for these terms. This complicates the use of the factory (since now the caller must know the default types), but it means the factory does not have to be bootstrapped.

Bootstrapping requires that we create the most primitive "root types." For instance we create SYMBOL as a symbol with type ^ROOT.

// Let's create a "normal" symbol.
val fact = TermFactory::new();
val symbol = fact.new_symbol(INTERNAL, "SYMBOL", fact.the_root);
val normal = fact.new_symbol(INTERNAL, "normal", symbol);

This code creates the root type SYMBOL and then uses it to create a normal symbol.

The same logic applies for the Boolean literals.

// Let's create the Boolean literals.
val fact = TermFactory::new();
val boolean = fact.new_symbol(INTERNAL, "BOOLEAN", fact.the_root);
val true = fact.new_boolean(INTERNAL, true, boolean);
val false = fact.new_boolean(INTERNAL, false, boolean);

The INTERNAL argument specifies the locus of the term. Every term has an associated locus, which specifies the place where the term originates. This can be a line in a file or on the console, or it can be INTERNAL.

Arc

Every term is delivered as an Arc<Term>, or an atomically reference counted object. Terms are cloned when stored. Loci do not need to be cloned, since a given locus (with the exception of INTERNAL) is unique to the term.

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