diff --git a/kmath-ast/src/commonMain/kotlin/scientifik/kmath/ast/MSTExpression.kt b/kmath-ast/src/commonMain/kotlin/scientifik/kmath/ast/MSTExpression.kt
index c0f124a35..3ee454b2a 100644
--- a/kmath-ast/src/commonMain/kotlin/scientifik/kmath/ast/MSTExpression.kt
+++ b/kmath-ast/src/commonMain/kotlin/scientifik/kmath/ast/MSTExpression.kt
@@ -4,7 +4,7 @@ import scientifik.kmath.expressions.Expression
 import scientifik.kmath.operations.NumericAlgebra
 
 /**
- * The expression evaluates MST on-flight
+ * The expression evaluates MST on-flight. Should be much faster than functional expression, but slower than ASM-generated expressions.
  */
 class MSTExpression<T>(val algebra: NumericAlgebra<T>, val mst: MST) : Expression<T> {
 
diff --git a/kmath-ast/src/jvmMain/kotlin/scientifik/kmath/ast/parser.kt b/kmath-ast/src/jvmMain/kotlin/scientifik/kmath/ast/parser.kt
index dcab1c972..cec61a8ff 100644
--- a/kmath-ast/src/jvmMain/kotlin/scientifik/kmath/ast/parser.kt
+++ b/kmath-ast/src/jvmMain/kotlin/scientifik/kmath/ast/parser.kt
@@ -12,6 +12,9 @@ import scientifik.kmath.operations.PowerOperations
 import scientifik.kmath.operations.RingOperations
 import scientifik.kmath.operations.SpaceOperations
 
+/**
+ * TODO move to common
+ */
 private object ArithmeticsEvaluator : Grammar<MST>() {
     val num by token("-?[\\d.]+(?:[eE]-?\\d+)?")
     val lpar by token("\\(")