L2

Lecture 2: (Embedded) Domain Specific Languages

Lecture slides

Below is just a "table of contents" for the lecture.

Learning outcomes for L2

This lecture we will focus on the following subset of the full AFP course learning outcomes:

• DSL: design embedded domain specific languages
  • DSL.Concepts: (abstract) syntax, semantics, ...
  • DSL.Implement: implement EDSLs in Haskell (as combinator libraries)
• Types: read, understand and extend Haskell programs which use advanced type system features
  • Types.Class: type classes, newtypes, deriving, ...
• Expl: explain and discuss the above topics

Anatomy of an EDSL

Primitive and derived operations

Think about: Compositionality, Abstraction

Implementation of an EDSL

Shallow embedding of Signals

Deep embedding of Signals

Deep versus Shallow

Case Study: A language for Shapes, v1

A language for Shapes, v2

More on the interfaces

Side track: A matrix library

Shallow embedding

Shallow embedding, continued

Deep embedding

Deep embedding, without GADT for reference

Deep embedding, cont.

Abstraction!

More interesting run function: render as ASCII-art

Connect back to to Signals

Discussion

Summary

• Different kinds of operations
  • constructor functions, combinators, run functions
• Implementation styles
  • Shallow: representation given by the semantics
  • Deep: representation given by the syntax
• Remember
  • Compositionality
  • Abstraction