The Spoofax Language Workbench provides tools for defining domain-specific languages (DSLs) with specialized syntax, semantics, and editor services. It offers declarative syntax definition with SDF, model transformations, static analysis for error checking, and semantic services for editors like content completion and error marking. Spoofax aims to make implementing these DSL features cheaply and integrates language development and use into the Eclipse IDE.

1. The Spoofax
Language Workbench
Eelco Visser
Lennart Kats
Spoofax tutorial hands-on material: www.strategoxt.org/Spoofax/Devnology

2. Spoofax
hands-on material:
www.strategoxt.org/Spoofax/Devnology

3. Domain-Specific
Languages (DSLs)
Domain:
• Mobile phone
• Web
• Financial
• Printer design
• ...
Spoofax tutorial hands-on material: www.strategoxt.org/Spoofax/Devnology
Can offer:
• Specialized syntax
• Specialized analysis
• Specialized
optimizations
• Platform independence

4. Example DSL:
Spoofax tutorial hands-on material: www.strategoxt.org/Spoofax/Devnology

5. Syntax definition
★ concrete + abstract syntax
Static semantics
★ error checking
★ name resolution
★ type analysis
Model-to-model transformation
★ express constructs in core language
Code generation
★ translate core language models to implementation
Problem: building DSLs
parser
generators
meta-
programming
languages
meta-
programming
libraries
template
engines
Spoofax tutorial hands-on material: www.strategoxt.org/Spoofax/Devnology

6. Problem: building DSLs (ct’d)
Spoofax tutorial hands-on material: www.strategoxt.org/Spoofax/Devnology

7. Editor Services
syntactic editor services
• syntax highlighting
• syntax checking
• outline view
• bracket matching, insertion
• automatic indentation
• syntax completion
• ...
semantic editor services
• error marking
• reference resolving
• hover help
• mark occurrences
• content completion
• refactoring
• ...
Spoofax tutorial hands-on material: www.strategoxt.org/Spoofax/Devnology

8. Syntax definition
Static semantics
Model-to-model transformation
Code generation
Syntactic Editor Services
Semantic Editor Services
}Spoofax
how can we make these things cheaply?
Spoofax tutorial hands-on material: www.strategoxt.org/Spoofax/Devnology

9. • <spoofax screenshot: lang def and lang use
in Eclipse workspace>
Spoofax tutorial hands-on material: www.strategoxt.org/Spoofax/Devnology

10. #1 Syntax definition
• Basic expression language
1+2+3
Expr “+” Expr -> Expr {cons(“Plus”)}
Spoofax tutorial hands-on material: www.strategoxt.org/Spoofax/Devnology

11. #1 Syntax definition
• Basic expression language
1+2+3
2
1
3
+
+
21
3
+
+
is that or ?
what does the abstract syntax view say?

12. #1 Syntax definition
• Basic expression language
1+2*3
2
1
3
+
*
21
3
*is that or ?
what does the abstract syntax view say?
+

13. The Spoofax Solution:
Declarative Syntax with SDF
Declarative, explicit disambigation rules
Clean abstract syntax
Composable syntax definitions

14. #2 Transformation
Tip. Some other operators:
subtS, mulS, divS, gt, lt, eq
Transform 1+2 to <addition of> 1 and 2:
calc:
Add(Int(i), Int(j)) -> Int(<addS> (i, j))

15. #2 Transformation
Transform 1+2 to <addition of> 1 and 2:
calc:
Add(Int(i), Int(j)) -> Int(<addS> (i, j))
calculate = bottomup(try(calc))
Tip. Some other operators:
subtS, mulS, divS, gt, lt, eq

16. #3 Equations
New syntax
New semantics
x = 2
y = 3
result = 90 * x + 30 * y

17. #3 Equations
x = 2
y = 3
result = 90 * x + 30 * y
Assign(“x”, INT(2))
calc: Assign(x, e) -> e
where rules(GetValue: x -> e)
calc: Var(x) -> <GetValue> x
New syntax
New semantics

18. x = 2
y = 3
result = 90 * x + 30 * z
#4 Error markers
(Var(“z”), “Variable z is not defined”)
transform

19. #4 Error markers
analyze = topdown(try(record-var))
record-var:
Assign(x, e) -> Assign(x, e)
with
rules(
GetVar :+ x -> e
)
constraint-errors = collect-all(constraint-error, conc)
constraint-error:
Var(x) -> (x, $[Variable [x] is not defined])
where
not(<GetVar> x)

20. #4 Error markers
#5 Refinement
analyze = topdown(try(record-var))
record-var:
Assign(x, e) -> Assign(x, e)
with
rules(
GetVar :+ x -> e
)
constraint-errors = collect-all(constraint-error, conc)
constraint-error:
Var(x) -> (x, $[Variable [x] is not defined])
where
not(<GetVar> x)

21. #4 Error markers
#5 Refinement
editor-resolve:
(Var(x), position, ast, path, project-path) -> target
where
target := <GetVar> x
editor-complete:
(Var(x), position, ast, path, project-path) -> proposals
where
proposals := <all-keys-GetVar> x

22. Refinement &
Free play

23. Syntax definition
Static semantics
Model-to-model transformation
Code generation
Syntactic Editor Services
Semantic Editor Services
}Spoofax
www.spoofax.org