module Spoofax-Propositional-Language

/** md:
Title: Concrete Syntax

## Concrete Syntax

The current Spoofax/Eclipse IDE is oriented around individual language
projects. Therefore in order to work with ASTs of the SPL
[abstract syntax](../README.md#abstract-syntax) that we just saw, it's easiest to
define a concrete syntax for SPL, via the following SDF3 definition:

*[SPL]: Spoofax Propositional Language

```sdf3
**/

imports
  
  Common

context-free sorts

  Prop String

context-free start-symbols

  Prop

/** md (include the following code in the documentation) */
context-free syntax
  
  Prop.True  = <1>
  Prop.False = <0>
  Prop.Atom  = String
  Prop.Not   = <!<Prop>>
  Prop.And   = <<Prop> & <Prop>>
  Prop.Or    = <<Prop> | <Prop>>
  Prop.Impl  = [[Prop] -> [Prop]]
  Prop.Eq    = <<Prop> = <Prop>>
  Prop       = <(<Prop>)> {bracket}
  
  String = ID

context-free priorities

  Prop.Not
  > Prop.And
  > Prop.Or
  > Prop.Impl
  > Prop.Eq
/* [stop to avoid the open-comment in the extracted markdown] **/

/** md [conclusion of the documentation]
```

Thus, the first two example AST expressions

`A: {! examples/sec4.1_A.aterm !}` and
`B: {! examples/sec4.1_B.aterm !}`

from {! ../docrefs/sec4.1.md !} can be generated by the following much more
compact SPL expressions:

`A: {! examples/sec4.1_A.spl !}` and
`B: {! examples/sec4.1_B.spl !}`. (If you are following along in the repository,
you can visit the file `syntax/examples/sec4.1_A.spl` (or ...`_B.spl`) and from the
Spoofax menu select "Syntax > Show parsed AST" to see the AST generation
in action.)

This concrete syntax actually makes it easier to construct the example
expressions used throughout the tutorial manual as examples for Stratego
processing.
**/