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A VS Code extension which provides language support for Logtalk.

Features | Configurations | Bug Reporting

Note before installation

This extension can be installed via extensions viewlet of VS Code or 'Extensions: install extension' command from the command palette. The author notices that it is developed and tested in Logtalk 3.12.0 and VS Code 1.17 on Debian 9.0 (stretch). It's not yet tested under other environments.


Feature descriptions and usages

Syntax highlighting

  • Full syntax highlight for all Logtalk built-in control constructs, directives, methods, and predicates
  • Full syntax highlight for all ISO Prolog standard built-in control constructs, directives, and predicates
  • Built-ins pattern support

Indentation, snippets and auto-completion

  • Indentation after new line
  • Built-in directive, method and predicate template auto-completion
  • Auto-complete recursive parameters: When '.'(dot) occures as first non-space character, VSC-Logtalk will repeat the nearest above head of clause and automatically change the parameters if possible.

Note: Relations between entities use choice snippets. 'orel' triggers object relation choices and 'crel' for category. There is only one relation between protocols 'extends', so 'ext' will trigger the snippet.

The snippets for built-ins all are triggered by natural prefix, i.e. ':- public' triggers ':- public()' directive. You needn't to type all charaters to show up the suggestion list.

Refter to the table below for other snippets:

Prefix Description
:- obj Object
:- cat Category
:- pro Protocol
orel relations between objects(choice)
crel relations between categories(choice)
ext relations between categories
category Category with protocol
category Category
class Class with all
class Class with category
class Class with metaclass
class Class with protocol
class Class
category Complementing category
category Extended category
protocol Extended protocol
instance Instance with all
instance Instance with category
instance Instance with protocol
instance Instance
private (with no arguments)
private Private predicate
protected (with no arguments)
protected Protected predicate
protocol Protocol
object Prototype with all
object Prototype with category
object Prototype with parent
object Prototype with protocol
object Prototype
public (with no arguments)
public Public predicate


Grammar linter

  • The grammar errors (if any) will display in OUTPUT channel when active source file is saved.

  • Command 'Goto next/previous error': see section Commands below.



Project specified commands

Project specified commands can be triggered from command palette via entering 'logtalk' to pop up the list of all commands of VSC-Logtalk.

Command Description Key binding
Open Logtalk Opens Logtalk in an integrated terminal alt-x o
Run Testers Runs the logtalk_tester script on the project root directory
Run Doclets Runs the logtalk_doclet script on the project root directory

Source file specified commands

These commands can be triggered from editor/context and explorer/context menus via right click editor area or Logtalk files in explorer area respectively. In explorer context, the file name at which right click occurs will be passed in the command as argument. File specified commands can also be triggered from command palette so that active file name in the editor will be passed in the command.

Command Description Key binding
Load Document Loads the active source file into the Logtalk process F9
Run Tests Runs the tester file under the active source file directory
Run Doclet Run the doclet file under the active source file directory
Goto Next/Previous Error Locate cursor to the nearest line with error/warning from current cursor location and the corresponding error/warning message displays in output channel F7/shift-F7
Scan Dead Code Scans active file for dead code
Generate Documentation Generates documentation for the files under the active source file directory
Generate Diagrams Generates diagrams for the files under the active source file directory
  • Command 'Logtalk: load document'



  • The user can configure settings via VS Code menu File/Preferences/Settings. Entering 'logtalk' in the input box will show up Logtalk settings. The settings in this extension with their default values are:

    • "logtalk.executable": "/usr/local/bin/logtalk"

      This setting points to the Logtalk executable, which can be created by running the logtalk_backend_select script. In alternative, use the absolute path to the integration script you want to use, e.g. swilgt or

    • "logtalk.executable.arguments": [ ]

      Arguments of Logtalk executable run in terminal.

    • "logtalk.tester.script": "/usr/local/bin/logtalk_tester"

      Automation script for running tests.

    • "logtalk.tester.arguments": [ ]

      Arguments for the automation script for running tests.

    • "logtalk.doclet.script": "/usr/local/bin/logtalk_doclet"

      Automation script for running doclets.

    • "logtalk.documentation.arguments": [ ]

      Arguments for the automation script for running doclets.

    • "logtalk.documentation.script": "/usr/local/bin/lgt2html"

      Script for converting the XML files generated by the Logtalk lgtdoc tool.

    • "logtalk.documentation.arguments": [ ]

      Arguments for the script that converts the XML files generated by the Logtalk lgtdoc tool.

    • "logtalk.graphviz.executable": "/usr/local/bin/dot"

      Graphviz executable for converting the .dot files generated by the Logtalk diagrams tool.

    • "logtalk.graphviz.arguments": ["-Tsvg"]

      Arguments for the Graphviz executable that converts the .dot files generated by the Logtalk diagrams tool.

    • "logtalk.graphviz.extension": ["svg"]

      File name extension for the diagram files generated by the Graphviz executable.

Bug reporting

Feel free to report bugs or suggestions via issues


Pull requests are welcome.


The author of this extension thanks Professor Paulo Moura who is the author of Logtalk for his patient help and support. Syntax highlighting, some snippets, and some commands are integrated from his distro of Logtalk.