Modular Extension ofDomain-specific Languages

Thomas Degueule

Software Analysis & Transformation

CWI

https://tdegueul.github.io

CWI Scientific Meeting

24 November 2017

Modular Extension of Executable DSLs 1 / 9

▪ Joint work with the DiverSE group @ Inria

▪ CWI—Inria associate team Agile Language Engineering (ALE)

Foreword

20th ACM/IEEE International Conference on

Model-driven Engineering Languages and Systems

Modular Extension of Executable DSLs 2 / 9

VHDLHardware Description Language

CapellaSystems Engineering Language

ScratchProgramming for Kids

Node-REDWiring the Internet of Things

Modular Extension of Executable DSLs 3 / 9

Abstract Syntax

Modular Extension of Executable DSLs 3 / 9

Abstract Syntax

Concrete Syntax

Modular Extension of Executable DSLs 3 / 9

Abstract Syntax

Concrete Syntax

Execution Semantics

Modular Extension of Executable DSLs 3 / 9

Abstract Syntax

Execution Semantics

Modular Extension of Executable DSLs 3 / 9

AST Classes

Abstract Syntax

Execution Semantics

Modular Extension of Executable DSLs 3 / 9

AST Classes

Abstract Syntax

Execution Semantics

Modular Extension of Executable DSLs 3 / 9

Interpreter Pattern

Visitor Pattern

AST Classes

Abstract Syntax

Execution Semantics

Modular Extension of Executable DSLs 3 / 9

AST Classes

Abstract Syntax

Execution Semantics

Printing Semantics

Modular Extension of Executable DSLs 3 / 9

Interpreter Pattern

Visitor Pattern

AST Classes

Abstract Syntax

Execution Semantics

Printing Semantics

Modular Extension of Executable DSLs 3 / 9

AST Classes

Execution Semantics

Abstract Syntax

Modular Extension of Executable DSLs 3 / 9

Interpreter Pattern

Visitor Pattern

AST Classes

Execution Semantics

Abstract Syntax

Modular Extension of Executable DSLs 4 / 9

▪ How to extend (syntax and semantics of) DSLs

1. Without anticipating the extension

2. Without modifying or duplicating existing code

3. While ensuring type safety

Challenges of Modular Extensioncf. The Expression Problem

Philip Wadler

1998

Syntax

Semantics

FSM GuardedFSM

ExecGuardedFSMExecFSM

The REVISITOR Pattern

Modular Extension of Executable DSLs 5 / 9

▪ Maps syntactic objects to abstract semantic types

Revisitor Interface

Modular Extension of Executable DSLs 5 / 9

▪ Maps syntactic objects to abstract semantic types

Revisitor Interface

Modular Extension of Executable DSLs 6 / 9

▪ Implements the semantic objects

Revisitor Implementation

Modular Extension of Executable DSLs 7 / 9

Modular Extension with Revisitors

Modular Extension of Executable DSLs 7 / 9

Modular Extension with Revisitors

Extend the (existing) mapping

Modular Extension of Executable DSLs 7 / 9

Modular Extension with Revisitors

Extend the (existing) mapping

Extend the (existing) semantics

Modular Extension of Executable DSLs 8 / 9

ALE: the Action Language for EMF

[EclipseCon’17] EcoreTools Next:

Executable DSL made (more) accessible

https://tinyurl.com/ale-ecorePrinting FSMs in ALE

Modular Extension of Executable DSLs 9 / 9

▪ The story so far

• Independent and modular extensibility of syntax & semantics

• With incremental compilation, without anticipation

• Applicable in any “mainstream” OO language

• The ALE language, soon™ in Eclipse, makes it user-friendly

▪ What’s next?

• Separate compilation is the first step towards language components

• Off-the-shelf language components have explicit provided & required interfaces

• Pick, assemble, and customize language components to create new DSLs

Wrap-up

choose produce

DSL1

DSL2

DSLn

EOF