Remove concatination from the builder, it's now the duty of the internal method

src/parser/builder_api.nim

@@ -11,9 +11,9 @@ proc tryParseBuild*[T](
   builder: Builder[T],
   builderFns: seq[tuple[
     parserFn: Parser -> ParserResult,
-    concatFn: (seq[ParserToken], seq[T]) -> seq[T],
+    builderFn: seq[ParserToken] -> seq[T],
   ]],
-  defaultBuilderFn: (seq[ParserToken]) -> seq[T],
+  defaultBuilderFn: seq[ParserToken] -> seq[T],
   stopAtParserFn = newline,
 ): BuilderResult[T] =
   ## Parse remaining text in `builder` by going checking in the `builderFns` list for a sucessful `parserFn`.
@@ -32,8 +32,8 @@ proc tryParseBuild*[T](
 
     # Find the first matching parser and convert its tokens
     var found = false
-    for builderFn in builderFns:
-      let (parserFn, concatFn) = builderFn
+    for fn in builderFns:
+      let (parserFn, builderFn) = fn
 
       let parseResult = emptyParser.flatMap(parserFn)
       if parseResult.isOk():
@@ -50,10 +50,11 @@ proc tryParseBuild*[T](
         parserAcc = parseResult.map(emptyTokens)
         builderAcc = builder.initBuilder(
           okParser,
-          concatFn(
-            okParser.tokens,
-            builderAcc[1] & defaultBuilderTokens,
-          ),
+          concat(
+            builderAcc[1],
+            defaultBuilderTokens,
+            builderFn(okParser.tokens),
+          )
         )
         break
 
@@ -68,5 +69,8 @@ proc tryParseBuild*[T](
 
   BuilderResult[T].ok(builder.initBuilder(
     builderAcc[0],
-    builderAcc[1] & defaultBuilderTokens,
+    concat(
+      builderAcc[1],
+      defaultBuilderTokens,
+    ),
   ))