Add JSON dFoldL

src/Parser/JSON.md

@@ -82,6 +82,30 @@ Eq (JSONValue t) where
 %hide Language.Reflection.TT.WithFC.value
 ```
 
+### JSON Functions
+
+`foldl` Analog for consuming a JSON structure by values. Ignores the keys in
+objects.
+
+```idris
+export
+dFoldL : {t : JSONType} 
+  -> (acc -> (type : JSONType) -> (val : JSONValue type) -> acc) 
+  -> acc -> JSONValue t -> acc
+dFoldL f acc' (VObject xs) = 
+  let recur : acc -> (v : JSONType) -> (String, JSONValue v) -> acc
+      recur acc' v (key, value) = dFoldL f acc' value
+  in DList.dFoldL recur acc' xs
+dFoldL f acc' (VArray xs) = 
+  let recur : acc -> (v : JSONType) -> JSONValue v -> acc
+      recur acc' v value = dFoldL f acc' value
+  in DList.dFoldL recur acc' xs
+dFoldL f acc (VString s) = f acc _ (VString s)
+dFoldL f acc (VNumber d) = f acc _ (VNumber d)
+dFoldL f acc (VBool b) = f acc _ (VBool b)
+dFoldL f acc VNull = f acc _ VNull
+```
+
 ## Parsers
 
 We are going to get mutually recursive here. Instead of using a `mutual` block,