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Linking to Concepts

rascal-0.42.1

Synopsis​

Refer to a concept in this course or another course.

Syntax​

((ConceptName))
((ParentConceptName-ConceptName))
((FullDashSeparatedPathTo-ConceptName))
((Course))
((Course:ConceptName))
((Course:ParentConceptName-ConceptName))
((Course:FullDashSeparatedPathTo-ConceptName))
((ModuleName))
((a::b::ModuleName))
((Course:a::b::ModuleName))
((module:ModuleName))
((module:a::b::ModuleName))
((Course:module:a::b::ModuleName))
((package:a::b))
((Course:package:a::b))
((data:ADTName))
((syntax::SyntaxName))
((function::functionName))

And also for all of the above the labeled variants:

[a text label]((ConceptLink))

Description​

Above are all the ways a concept can be linked:

  • The concept name, which is equal to its file name is leading.
  • The parent concept name can be used to disambiguate
  • Otherwise the full path to the root of the course can be used, where / is replaced by -
  • Rascal modules can be referenced by name and by their fully qualified name
  • To disambiguate modules from concept names, the module and package prefixes come in handy.

Examples​

The concept name of this concept is ReferenceToConcept while its title is Reference to Concept (note the spaces).

We can create a reference to the CodeExamples concept in the current course in the following ways:

  • [Code Examples](/docs/Tutor/Markup/CodeExamples/) (using the display name) gives: "Code Examples".
  • [CodeExamples](/docs/Tutor/Markup/CodeExamples/) (using its parent concept name and concept name) gives "CodeExamples".
  • [see code examples](/docs/Tutor/Markup/CodeExamples/) gives "see inline markup"
  • for more link notations see the syntax types above.

When a link name is ambiguous this means that multiple concepts could be the target of the link. This can happen, for example, when:

  • The same name is used nested under different compound Concepts
  • The same name is used by different dependent libraries
  • A name occurs as different categories: concept, module, dunction, datatype, etc.
  • Or any combination of the above.

Here is an example error message caused by an ambiguous reference:

[ERROR] /courses/Recipes/UserInterfaces/LanguageServerProtocol/RegisterYourLanguage/RegisterYourLanguage.md:51:0: Ambiguous concept link `Syntax Definition` can be resolved by:
   * using [Syntax Definition](../../../Rascal/Declarations/SyntaxDefinition/index.md) to link to /Rascal/Declarations/SyntaxDefinition/index.md;
   * using [SyntaxDefinition](../../..//Library/lang/rascal/\syntax/Rascal.md#lang-rascal-\syntax-Rascal-SyntaxDefinition) to link to /Library/lang/rascal/\syntax/Rascal.md#lang-rascal-\syntax-Rascal-SyntaxDefinition;
   * using [SyntaxDefinition](../../..//Library/lang/rascal/tests/concrete/recovery/bugs/MultiErrorBug.md#lang-rascal-tests-concrete-recovery-bugs-MultiErrorBug-SyntaxDefinition) to link to /Library/lang/rascal/tests/concrete/recovery/bugs/MultiErrorBug.md#lang-rascal-tests-concrete-recovery-bugs-MultiErrorBug-SyntaxDefinition;

We see that the name resolves to a concept in the Rascal course, to a non-terminal name in the Rascal syntax definition itself, called "SyntaxDefinition", and to a local type definition in one of the test modules of the standard library. This is all accidental.

In short: the link "Syntax Definition" was just not precise enough. The error message helps by:

  • providing three options to choose from (or as many as their are alternative resolutions);
  • ensuring that each option resolves precisely and unambiguously to one of the original alternatives;
  • ensuring thet each option is the shortest way to describe the exact and unambiguous link. Their may be many more ways to write it.

Benefits​

  • Links are checked at compile-time
  • Ambiguous links are first tried in the local course scope before an ambiguity is reported
  • Ambiguous links have helpful error messages with the options to choose from