MPS
Domain Specific Languages
with pleasure
Václav Pech

JetBrains MPS
High thoughts must have high language.
Aristophanes

Your vocabulary reflects the way you think
Seth Godin

[Embedded Software]
mbeddr

[Data analysis]
MetaR

[Business Application]
Insurance Configuration Tool

[Business Application]
Insurance Configuration Tool

<no variables> <no parent>
<no libraries>
<no business objects>
<no parent>
[Business Application]
Insurance Configuration Tool

Notations for DSLs
● Text
● Diagrams
● Tables
● Forms
● Mixtures of all
● …

The number and the type of the basic colour
words of a language determine how one sees the
rain bow

Programs are trees
R
A B
C D
G
R
E F

Programs are trees
R
A B
C D
G
R
E F

Children have roles
R
A IfStatement
Expr StmtList
G
R
E F
condition body

References cross the tree
R
Routine def B
Call D
G
R
E F

Languages are sets of concepts
C1
C2
C3
Cn
L1
L2

Programs and Languages
R
A B
C D
G
R
E F
C1
C2
C3
Cn
L
Models consist of nodes
Meta-models consist of concepts

IntelliJ IDEA inspections

Groovy AST transformations

Groovy AST transformations

There's no life without trees
● Extending IDEs
● External DSLs
● Internal DSLs in modern languages
● Groovy AST transformations
● Scala macros
● Lisp, Clojure macros
● Lombok

Notations for DSLs
● Text
● Diagrams
● Tables
● Forms
● Mixtures of all
● …

Parsing is the bottleneck
… of language expressiveness

Editing text
Parsing

Programs are trees
R
A B
C D
G
R
E F
WhileLoop
MethodDef
MethodCall
L IfStatement
Models consist of nodes
Meta-models consist of concepts

Editing trees directly
Projecting

by Jens Nerche @jensnerche
Rich syntaxes

Combine languages

Multiple notations

Parsing is the bottleneck
… of language expressiveness
● Limits the possible syntaxes
● Allows only one editable code visualization
● Complicates combining languages

Aspects of language definition
● Abstract syntax
● Concrete syntax (editor)
● Static semantics
● Constraints
● Type-system
● Dataflow
● Execution semantics / Generator
● IDE support

Books
● http://books.campagnelab.org
● http://dslbook.org
https://www.jetbrains.com/mps/publications

Books
● http://books.campagnelab.org
● http://dslbook.org
← He is a Biologist!
https://www.jetbrains.com/mps/publications

The limits of language are the limits of one's world
Ludwig Wittgenstein

Questions
Want more?
http://www.jetbrains.com/mps
@vaclav_pech

Image credits
http://www.flickr.com/photos/horiavarlan/4329908160/sizes/m/in/photostream/
http://www.flickr.com/photos/pink_floyd/2409134519/sizes/m/in/photostream/
http://www.flickr.com/photos/atache/4124732863/sizes/m/in/photostream/
http://www.flickr.com/photos/a_ninjamonkey/3294014627/sizes/m/in/photostream/
http://www.flickr.com/photos/carlc/1968636137/
http://www.flickr.com/photos/tasuki/3503304405/sizes/m/in/photostream/
http://www.flickr.com/photos/bmwccgb/5069454884/sizes/m/in/photostream/
http://www.flickr.com/photos/rpmarks/3932013183/sizes/m/in/photostream/
http://www.flickr.com/photos/orqwith/4325166853/
https://www.flickr.com/photos/charlestilford/732688216