Editing SHACLC with shaclc-mode

• Source: https://github.com/VladimirAlexiev/shaclc-mode
• Author: Vladimir Alexiev, Ontotext Corp

Intro

Many people think that semantic models should be described with RDF Shapes, not just ontologies. SHACL is the W3C standard for specifying shapes, and SHEX is a popular competitive standard.

SHACL is very verbose because it expresses shapes as RDF triples. SHACL Compact Syntax (SHACLC) is a dedicated syntax modeled after SHEX that is a lot more compact and nicer to work with.

Just like there is shexc-mode for editing SHEX in Emacs, this creates a shaclc-mode (in fact this mostly borrows from shexc-mode).

Why SHACLC?

The easiest way to understand the benefits of SHACLC compared to SHACL is by looking at some example shapes from the euBusinessGraph semantic model:

• SHEX has a compact dedicated syntax (in addition to JSON and RDF representations): see ebg-shapes.shex, 143 lines

• SHACL is very verbose because all constructs are represented in triples: see ebg-shapes.shacl, 504 lines (the shot below shows only 6 properties of Company)

• SHACLC adds a compact dedicated syntax, so SHACLC schemas are easy to understand: see ebg-shapes.shaclc, 183 lines (35 lines are prefixes)

Features

• Syntax highlighting

• Syntax checking using flycheck and shaclconvert (see TQ SHACL below)

• Comment/uncomment block with M-;
• Index of shape definitions (imenu) and panel on the right (imenu-list)

Installing

• Optionally, byte compile shaclc-mode.el
• Add this to .emacs

(add-to-list 'load-path "{path-to-shaclc}")
(autoload 'shaclc-mode "shaclc-mode" "Major mode for SHACLC (SCHACL Compact Syntax)" t)
(add-to-list 'auto-mode-alist '("\\.\\(shaclc\\|shc\\)$" . shaclc-mode))

TQ SHACL

The TQ SHACL API implements SHACLC since June 2000.

Ontotext's shaclconvert tool is a simple CLI on top of the TQ API. It is not open sourced yet but we hope to merge it to TQ SHACL in the future.

Bugs and issues: https://github.com/TopQuadrant/shacl/search?q=shaclc&type=issues

Jena SHACL

Starting June 2020, Jena now includes SHACL and SHACLC processing in riot and a new command shacl:

• Documentation: https://jena.apache.org/documentation/shacl/
• Source: https://github.com/apache/jena/tree/main/jena-shacl
• Tests: https://github.com/apache/jena/tree/main/jena-shacl/src/test
  • SHACLC tests: https://github.com/apache/jena/tree/main/jena-shacl/src/test/files/shaclc-valid

Bugs and issues: https://issues.apache.org/jira/issues/?jql=text~shaclc

Todo

• Make an ELPA package
• Use SHACLC.g4 grammar to make highlighting better
• Merge shaclconvert to TopQuadrant SHACL
• Fix bugs in shaclconvert reading and writing
• Make SHACLC (see TopQuadrant/shacl#98) nearly lossless so it can be round-tripped with SHACL

Help wanted!