feat: Add Chapter 6

test/manual-suite.spt

@@ -32,6 +32,8 @@ for any of them if you want to try them that way. Just remember to add a
 
 Hopefully these examples are helpful to your exploration and understanding of
 Stratego -- certainly creating them was to mine.
+
+Additional notes on particular sections or tests follow.
 **/
 module manual-suite
 language Spoofax-Propositional-Language
@@ -91,3 +93,71 @@ test sec5_3_2_impl_nf_ex [[
                                              False())),
                             Impl(Atom("p"),False())),
                        False())
+
+/** md
+### Chapter 6
+
+Many of the examples in
+[Chapter 6](http://www.metaborg.org/en/latest/source/langdev/meta/lang/stratego/strategoxt/06-rules-and-strategies.html)
+are in the form of interactive "Stratego shell" sessions. For this repository, we
+have to convert them to rule definitions in a Stratego file (`chap6.str`) and
+test cases for each of the executed examples.
+
+Also, there are some examples for a Plus-Times signature; we transpose these
+to Or-And for the sake of keeping everything within the SPL language project.
+
+To illustrate extending a rule, we need to give the rule we're going to extend
+a different identifier and add both definitions to that (otherwise our original
+rule `SwapArgs` would already have been extended).
+
+The `chap6.str` file also includes a solution to the exercise in
+[Section 6.2](http://www.metaborg.org/en/latest/source/langdev/meta/lang/stratego/strategoxt/06-rules-and-strategies.html#what-is-a-strategy).
+On the other hand, it is not clear whether the Spoofax Eclipse IDE has a "debug"
+operator for Stratego, or if so how it would work, so the repository does not
+attempt to implement the "debug" example.
+
+The remainder of the chapter (from section 6.3 on) consists of general information
+about Stratego syntax and information about the Stratego compiler. As it's not
+clear if the latter applies to the Spoofax Eclipse IDE, there are no further test
+cases in this repository beyond Section 6.2.
+**/
+
+test sec6_1_swap_ex [[
+  p | 0
+]] run SwapArgs to Or(False(), Atom("p"))
+
+test sec6_1_swap_fails [[
+  p & 0
+]] run SwapArgs fails
+
+test sec6_1_swap_subterm_fails [[
+  (1 | p) & 0
+]] run SwapArgs fails
+
+test sec6_1_swap_only_outer_ex [[
+  (1 | p) | 0
+]] run SwapArgs to Or(False(), Or(True(), Atom("p")))
+
+test sec6_1_swapboth_or_ex [[
+  p | 0
+]] run SwapBoth to Or(False(), Atom("p"))
+
+test sec6_1_swapboth_and_ex [[
+  p & 0
+]] run SwapBoth to And(False(), Atom("p"))
+
+test sec6_2_invoke_rule_ex [[
+  1 -> p
+]] run DefI to Or(Not(True()), Atom("p"))
+
+test sec6_2_innermost_ex [[
+  p = q
+]] run dnf4 to Or(Or(And(Not(Atom("p")),Not(Atom("q"))),
+                     And(Not(Atom("p")),Atom("p"))),
+                  Or(And(Atom("q"),Not(Atom("q"))),
+                     And(Atom("q"),Atom("p"))))
+
+test sec6_2_dnf_exercise_ex [[
+  p = q
+]] run better-dnf to Or(And(Not(Atom("p")),Not(Atom("q"))),
+                        And(Atom("q"),Atom("p")))

trans/chap6.str

@@ -0,0 +1,18 @@
+module chap6
+imports prop-laws prop-eval2 signatures/-
+
+rules
+
+  SwapArgs : Or(e1,e2) -> Or(e2,e1)
+
+  SwapBoth : Or(e1,e2)  -> Or(e2,e1)
+  SwapBoth : And(e1,e2) -> And(e2,e1)
+
+  ExMid: And(Not(x),x) -> False()
+  ExMid: And(x,Not(x)) -> False()
+
+strategies
+
+  better-dnf =
+    innermost(DefI <+ DefE <+ ExMid <+ DAOL <+ DAOR <+ DN <+ DMA <+ DMO); eval-down
+

trans/spoofax_propositional_language.str

@@ -13,6 +13,7 @@ imports
   prop-laws
   prop-eval2
   prop-desugar
+  chap6
 
 rules // Debugging