Add transformer function

src/test.nim

@@ -268,6 +268,12 @@ proc merge[T](t: Builder[T], parser: Parser, tree: seq[T]): Builder[T] =
     tree
   ))
 
+proc mapTree[T](builder: BuilderResult[T], fn: seq[T] -> seq[T]): BuilderResult[T] =
+  builder.map(proc(b: Builder[T]): Builder[T] = Builder((
+    parser: b[0],
+    tree: fn(b[1]),
+  )))
+
 proc applyParsers[T](
   builder: Builder[T],
   parsers: seq[Parser -> ParserResult],
@@ -288,12 +294,13 @@ proc applyParsers[T](
     ),
   )
 
-proc mapTree[T](builder: BuilderResult[T], fn: seq[T] -> seq[T]): BuilderResult[T] =
-  builder.map(proc(b: Builder[T]): Builder[T] = Builder((
-    parser: b[0],
-    tree: fn(b[1]),
-  )))
-
+proc applyParsersSeq[T](
+  builder: BuilderResult[T],
+  xs: seq[tuple[
+    parsers: seq[Parser -> ParserResult],
+    tokenFoldFn: (seq[Token], seq[T]) -> seq[T],
+  ]]): BuilderResult[T] =
+    xs.foldl(a.flatMap((x: Builder[T]) => x.applyParsers(b[0], b[1])), builder)
 
 when isMainModule:
   let parseHeadingStars = @[
@@ -313,19 +320,24 @@ when isMainModule:
     return proc(xs: seq[Token], ys: seq[StringBuilderT]): seq[StringBuilderT] =
       return ys & xs.foldl(a & b.value, typeInfo)
 
-  let sampleBuilder: StringBuilderResult = StringBuilderResult
+  let sampleBuilder = StringBuilderResult
   .ok(StringBuilder((
     parser: initParser("**** Some stars"),
     tree: newSeq[StringBuilderT](),
   )))
-  .flatMap((x: StringBuilder) => x.applyParsers(
-    parsers = parseHeadingStars,
-    tokenFoldFn = stringConcat("Stars: ")
-  ))
-  .flatMap((x: StringBuilder) => x.applyParsers(
-    parsers = parseHeadingText,
-    tokenFoldFn = stringConcat("Text: ")
-  ))
+  .applyParsersSeq(@[
+    (parseHeadingStars, stringConcat("Stars: ")),
+    (parseHeadingText, stringConcat("Text: "))
+  ])
+
+  # .flatMap((x: StringBuilder) => x.applyParsers(
+  #   parsers = parseHeadingStars,
+  #   tokenFoldFn = stringConcat("Stars: ")
+  # ))
+  # .flatMap((x: StringBuilder) => x.applyParsers(
+  #   parsers = parseHeadingText,
+  #   tokenFoldFn = stringConcat("Text: ")
+  # ))
 
 
   echo sampleBuilder