fix: Astrid.Query.andThen compose with map*

Reserve stack slots for andThen values and fill them in later. The old
approach of a strict stack machine was wrong.

src/exec/fixtures/README.md

@@ -0,0 +1,127 @@
+
+# Query batching
+
+Step 1)
+    queries = [ (0, map3 fA (succeed x) (map fB (andThen (\_ -> succeed j) (succeed k))) (succeed y)) ]
+    values = [ Pending ]
+    callbacks = []
+Step 1.A)
+    query = map3 fA (succeed x) (map fB (andThen (\_ -> succeed j) (succeed k))) (succeed y) ]
+
+
+Step 2)
+    queries = [ (1, succeed x), (2, (map fB (andThen (\_ -> succeed j) (succeed k)))), (3, (succeed y)) ]
+    values = [Pending, Pending, Pending, Pending]
+    callbacks = [ (0, fA) ]
+
+Step 2.A)
+    query = (3, succeed y)
+
+Step 3)
+    queries = [ (1, succeed x), (2, (map fB (andThen (\_ -> succeed j) (succeed k)))), ]
+    values = [ Pending, Pending, Pending, Ready y ]
+    callbacks = [ (0, fA) ]
+
+Step 3.A)
+    query = (2, (map fB (andThen (\_ -> succeed j) (succeed k))))
+
+Step 4)
+    queries = [ (1, succeed x), (4, (andThen (\_ -> succeed j) (succeed k))) ]
+    values = [ Pending, Pending, Pending, Ready y, Pending ]
+    callbacks = [ (0, fA), (2, fB) ]
+
+Step 4.A)
+    query = (4, (andThen (\_ -> succeed j) (succeed k)))
+
+Step 5)
+    queries = [ (1, succeed x), (5, succeed k) ]
+    values = [ Pending, Pending, Pending, Ready y, Pending, Pending ]
+    callbacks = [ (0, fA), (2, fB), (4, andThen (\_ -> succeed j)) ]
+
+Step 5.A)
+    query = (5, succeed k)
+    -- insert the value into position 5
+    
+Step 6)
+    queries = [ (1, succeed x) ]
+    values = [ Pending, Pending, Pending, Ready y, Pending, Ready k ]
+    callbacks = [ (0, fA), (2, fB), (4, andThen (\_ -> succeed j)) ]
+
+Step 6.A)
+    query = (1, succeed x)
+    -- insert the value into position 1
+
+Step 6)
+    queries = []
+    values = [ Pending, Ready x, Pending, Ready y, Pending, Ready k ]
+    callbacks = [ (0, fA), (2, fB), (4, andThen (\_ -> succeed j)) ]
+
+> Now go to reduce phase
+
+Reduce Step 1)
+    queries = []
+    values = [ Pending, Ready x, Pending, Ready y, Pending, Ready k ]
+    callbacks = [ (0, fA), (2, fB), (4, andThen (\_ -> succeed j)) ]
+
+Reduce Step 1.A)
+    last = (4, andThen (\_ -> succeed j))
+    value = values.pop() -- It should always be ready
+    -- call the callback to get the new query
+    queries.push(4, succeed j)
+    
+Reduce Step 2)
+    queries = [ (4, succeed j) ]
+    values = [ Pending, Ready x, Pending, Ready y, Pending ]
+    callbacks = [ (0, fA), (2, fB) ]
+
+Reduce Step 2.A)
+    -- check that we have 1 arg ready at end of stack, no, so break the reduce step
+
+
+> Now go back to query phase
+
+Step 7)
+    queries = [ (4, succeed j) ]
+    values = [ Pending, Ready x, Pending, Ready y, Pending ]
+    callbacks = [ (0, fA), (2, fB) ]
+
+Step 7.A)
+    query = (4, succeed j)
+    -- place value in slot 4
+
+Step 8)
+    queries = []
+    values = [ Pending, Ready x, Pending, Ready y, Ready j ]
+    callbacks = [ (0, fA), (2, fB) ]
+
+> Now go to reduce phase
+
+Reduce Step 3)
+    queries = []
+    values = [ Pending, Ready x, Pending, Ready y, Ready j ]
+    callbacks = [ (0, fA), (2, fB) ]
+
+Reduece Step 3.A)
+    last = (2, fB)
+    -- We look at last 1 arg
+    args = [ Ready j ]
+    -- place (fB j) in slot 2
+
+Reduce Step 4)
+    queries = []
+    values = [ Pending, Ready x, Ready (fB j), Ready y ]
+    callbacks = [ (0, fA) ]
+
+Reduece Step 4.A)
+    last = (0, fA)
+    -- We look at last 3 args
+    args = [ Ready x, Ready (fB j), Ready y ]
+    -- They are all ready
+    -- place (fA x (fB j) y) in slot 0
+
+Reduce Step 5)
+    queries = []
+    values = [ Ready (fA x (fB j) y) ]
+    callbacks = []
+
+-- Termination criteria reached, return values[0]

src/exec/mod.rs

@@ -210,11 +210,15 @@ pub(crate) fn exec(
                 )
                 .replace(
                     "var $author$project$Astrid$Query$map2 = F3(\n\tfunction (f, a, b) {\n\t\treturn $author$project$Astrid$Query$Dummy;\n\t});",
-                    r#"var $author$project$Astrid$Query$map3 = _Query_map2;"#,
+                    r#"var $author$project$Astrid$Query$map2 = _Query_map2;"#,
                 )
                 .replace(
                     "var $author$project$Astrid$Query$map = F2(\n\tfunction (f, a) {\n\t\treturn $author$project$Astrid$Query$Dummy;\n\t});",
-                    r#"var $author$project$Astrid$Query$map3 = _Query_map1;"#,
+                    r#"var $author$project$Astrid$Query$map = _Query_map1;"#,
+                )
+                .replace(
+                    "var $author$project$Astrid$Query$andThen = F2(\n\tfunction (f, q) {\n\t\treturn $author$project$Astrid$Query$Dummy;\n\t});",
+                    r#"var $author$project$Astrid$Query$andThen = _Query_andThen;"#,
                 );
 
             // final_script.replace("var $author$project$Astrid$Query$run = ", "JSON.stringify(x)");