Slides from DSL tutorial at Progressive F# Tutorials in NYC June 2012

1. Domain-Specific Languages
Phillip Trelford
Tomas Petricek
Progressive F# Tutorials NYC 2012

2. Thoughtworks Tech Radar 2012
F# Languages
“F# is excellent at concisely
expressing business and
domain logic.”

3. UML Sequence Diagrams
let fred = Object("FredrnPatron")
let bob = Object("BobrnWaiter")
let hank = Object("HankrnCook")
let renee = Object("ReneernCashier")

4. Types
F# UML Class Diagram
type Object(name) =
member this.Name = name
type Action =
| Call of Object * string *Object
| Async of Object * string *Object

5. Functional Program Layout
Types
Functions
API

6. DSLs for Testing
Internal DSL (NaturalSpec) External DSL (Gherkin)
• [<Scenario>] • Given I input 5
• let ``When calculating factorial of • When calculating the factorial
5 it should equal 120``() = • Then the result is 120
• Given 5
• |> When calculating factorial
• |> It should equal 120
• |> Verify

7. Learn More
• FParsec: http://www.quanttec.com/fparsec/
• FSLex /FsYacc:
http://fsharppowerpack.codeplex.com/