How do I create a customized file scheme in RascalMPL, like so |somescheme:///|, I couldn't find any resource on how that can be done?
In Rascal directly you can create schemes using the register locations function. This basically adds the schemes and authority (hostnames) to the registrar such that they can be resolved at IO time. Examples of this can be found in
lang::java::jdt::M3::Core etc.
You can also add new schemes in Java code by either registering a ILogicalSourceLocationResolver dynamically calling a method of URIResolverRegistry.getInstance(), or injecting an implementation of ISourceLocationInputResolver via adding its fully qualified class name to a file called org/rascalmpl/uri/resolvers.config. Examples of this can be found in the Rascal project and Rascal-eclipse project.