core: nom and surround

src/Parser/Interface.md

@@ -198,6 +198,7 @@ Lift a parser producing a `List` or `List1` of `Char` into a parser producing a
 `String`
 
 ```idris
+-- TODO: Rename these
 export
 parseString : Parser (List Char) -> Parser String
 parseString x = do
@@ -250,6 +251,40 @@ exactString str with (asList str)
     pure input
 ```
 
+Wrap a parser in delimiter characters, discarding the value of the delimiters
+
+```idris
+export
+delimited : (before, after : Char) -> Parser a -> Parser a
+delimited before after x = do
+  starting_state <- save
+  _ <- parseExactChar before
+  val <- x
+  Just _ <- tryMaybe $ parseExactChar after
+    | _ => throw $
+      MkParseError starting_state "Unmatched delimiter \{show before}"
+  pure val
+```
+
+Consume any number of characters of the provided character class and discard the
+result. Also a version for doing so on both sides of a provided parser
+
+```idris
+export
+nom : Parser Char -> Parser ()
+nom x = do
+  _ <- many x
+  pure ()
+
+export
+surround : (around : Parser Char) -> (item : Parser a) -> Parser a
+surround around item = do
+  nom around
+  val <- item
+  nom around
+  pure val
+```
+
 ### Composition of boolean functions
 
 ```idris