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>>  {left}
  Prop.Or    = <<Prop> | <Prop>>  {left}
  Prop.Impl  = [[Prop] -> [Prop]] {right}
  Prop.Eq    = <<Prop> = <Prop>>  {non-assoc}
  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.)

**/