Feature support record representation

type-class-schema/README.md

@@ -31,3 +31,20 @@ We'd like to support the following operations:
 - projection 
 - cartesian product
 - inner join
+
+## Record representation
+
+We have a few options of how to store record values:
+- tuples;
+- `JsonObject`;
+- `Map[String, Any]`;
+- ...
+
+In order to generalize storage we might use a type class `RecordRepr` that captures the operations that are required to compose record value and extract column values.
+
+```scala
+trait RecordRepr[A]:
+  type Prepend[HS, HV, S <:Tuple, A]
+  inline def prepend[HS, HV, S <:Tuple](h: HV, value: ValueWithSchema[S, A])(using SchemaValueType[HS *: S, A]): Prepend[HS, HV, S, A] 
+  inline def get
+```

type-class-schema/src/main/scala/ru/primetalk/typed/ontology/typeclass/rschema/RecordRepr.scala

@@ -0,0 +1,50 @@
+package ru.primetalk.typed.ontology.typeclass.rschema
+
+import ru.primetalk.typed.ontology.typeclass.schema.{SchemaValueType, ValueWithSchema}
+trait RecordRepr[Base]:
+  /**
+    * Type after prepending column of schema HS with value type HV to
+    * an existing schema S with value representation A
+    */
+  type Prepend[HS, HV, S <: Tuple, A <: Base]
+  inline def prepend[HS, HV, S <:Tuple, A <: Base](h: HV, value: ValueWithSchema[S, A])(using SchemaValueType[S, A]): Prepend[HS, HV, S, A] 
+
+  /**
+    * Type result of getting value from schema. Usually it's HV | Nothing
+    */
+  type Get[HS, HV, S <: Tuple, A <: Base] <: HV | Nothing
+  inline def get[HS, HV, S <: Tuple, A <: Base](value: ValueWithSchema[S, A]): Get[HS, HV, S, A]
+
+  inline def getOpt[HS, HV, S <: Tuple, A <: Base](value: ValueWithSchema[S, A]): Option[HV]
+
+
+object TupleReprs:
+  type Get0[HS, HV, S <: Tuple] <: HV | Nothing = S match 
+    case HS *: tail => HV
+    case _  *: tail => Get0[HS, HV, tail]
+    case EmptyTuple => Nothing
+
+  type Get0Opt[HS, HV, S <: Tuple] <: Option[HV] = S match 
+    case HS *: tail => Some[HV]
+    case _  *: tail => Get0Opt[HS, HV, tail]
+    case EmptyTuple => None.type
+
+  given RecordRepr[Tuple] = new RecordRepr[Tuple]:
+    type Prepend[HS, HV, S <: Tuple, A <: Tuple] = 
+      HV *: A
+    inline def prepend[HS, HV, S <: Tuple, A <: Tuple](h: HV, value: ValueWithSchema[S, A])(using SchemaValueType[S, A]): Prepend[HS, HV, S, A] =
+      h *: value.value
+
+    type Get[HS, HV, S <: Tuple, A <: Tuple] = Get0[HS, HV, S]
+    inline def get[HS, HV, S <: Tuple, A <: Tuple](value: ValueWithSchema[S, A]): Get[HS, HV, S, A] =
+      inline scala.compiletime.erasedValue[S] match
+        case _: (HS *: tail) => (value.value.head).asInstanceOf[HV]
+        case _: (_  *: tail) => get(value.value.tail)
+        case _: EmptyTuple   => ???
+
+
+    inline def getOpt[HS, HV, S <: Tuple, A <: Tuple](value: ValueWithSchema[S, A]): Option[HV] =
+      inline scala.compiletime.erasedValue[S] match
+        case _: (HS *: tail) => Some((value.value.head).asInstanceOf[HV])
+        case _: (_  *: tail) => getOpt(value.value.tail)
+        case _: EmptyTuple   => None

type-class-schema/src/main/scala/ru/primetalk/typed/ontology/typeclass/schema/ValueWithSchema.scala

@@ -14,6 +14,6 @@ object ValueWithSchema:
     new IdentityConversion[ValueWithSchema[Schema, Value]]
 
   extension [Schema, Value](vws: ValueWithSchema[Schema, Value])
-    def value: Value = vws
+    inline def value: Value = vws
 
 end ValueWithSchema