Ecosyste.ms: Awesome

An open API service indexing awesome lists of open source software.

Awesome Lists | Featured Topics | Projects

https://github.com/phipsgabler/dsl-examples

Shows examples of patterns used in Scala embedded DSLs.
https://github.com/phipsgabler/dsl-examples

dsl functional-programming scala

Last synced: 25 days ago
JSON representation

Shows examples of patterns used in Scala embedded DSLs.

Awesome Lists containing this project

README 

        
[![No Maintenance Intended](http://unmaintained.tech/badge.svg)](http://unmaintained.tech/)



# DSL-Examples #



Here I implement various showcases of Scala features, mostly related to DSLs, to

illustrate my bachelor's thesis.



Every example consists of a module object, containing all necessary definitions,

and a "test object" (inheriting from `App`), in which calls or constructions are

shown to typecheck or to work.



The "tests" should not be taken too seriously; they are only there to show how

the defined features can be used, not to ensure any invariants. Sometimes there aren't

even any.



## Usage ##



This is an SBT project; simply type `sbt console` on the top level. The package

`dsl_examples` is automatically imported. To play around with individual features,

you can import their module objects, like `import Logic._`.



# Description of Individual Examples #



## [ChurchList](src/main/scala/dsl_examples/ChurchList.scala) ##



An implementation of [church encoded](https://en.wikipedia.org/wiki/Church_encoding) lists, illustrating the hiding

of an internal implementation through an interface by `apply`/`unapply` in the companion object.



The interface is intended to look like the one of `List`: there are members `Empty` and `Cons`, as well as the

universal constructor `ChurchList`, which all can be pattern matched on.



## [Imperative](src/main/scala/dsl_examples/Imperative.scala) ##



Methods `repeat` and `_while`, to illustrate how blocks and by-name arguments can be used to construct functions

which look and behave like imperative language statements.



## [Logic](src/main/scala/dsl_examples/Logic.scala) ##



A small AST for predicate logic expressions, including an implementation function. Illustrates the use of operators and

extractors.



## [MutableDict](src/main/scala/dsl_examples/MutableDict.scala) ##



A mutable dictionary implementation based on a purely functional internal implementation, illustrating the getter/setter

syntax of Scala.



## [Range](src/main/scala/dsl_examples/Range.scala) ##



A wrapper for `Int`, reimplementing the syntax from

[`scala.collection.immutable.Range`](http://www.scala-lang.org/api/current/index.html#scala.collection.immutable.Range).



## [Read](src/main/scala/dsl_examples/Read.scala) ##



A simple example of a type class (inspired by Haskell's

[`Read`](http://hackage.haskell.org/package/base-4.8.0.0/docs/Prelude.html#t:Read)), providing the functionality of

reading a value of a type from a string.



## [Recover](src/main/scala/dsl_examples/Recover.scala) ##



A reimplementation of [`scala.util.Try`](http://www.scala-lang.org/api/current/index.html#scala.util.Try), illustrating

a usage of by-name parameters.



## [SExpParser](src/main/scala/dsl_examples/SExpParser.scala) ##



A small parser for [S-expressions](https://en.wikipedia.org/wiki/S-expression) (LISP syntax), using Scala's

parser combinators.



## [Delay](src/main/scala/dsl_examples/delay) ##



Multiple versions of delay objects (similar to [futures](https://en.wikipedia.org/wiki/Futures_and_promises), but not

actually using multi-threading).



- `Delay1` uses a mutable variable and hides its internal state.

- `Delay2` does in principle the same, but uses the Scala constructs for by-name arguments and lazy values.

- `Delay3` factors out the interface into a trait, and provides a monadic interface.

- `Delay4` is very similar to `Delay3`, but implements the monad type class from

  [`Scalaz`](https://github.com/scalaz/scalaz).



# License #



This stuff is available under the MIT license. See LICENSE.txt for more info.