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Simplify tuple types in Subset and Remover implementations #7

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Simplify tuple types in Subset and Remover implementations #7

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27 changes: 16 additions & 11 deletions core/src/main/scala/shapeful/tensor/TupleHelpers.scala
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Original file line number Diff line number Diff line change
Expand Up @@ -24,7 +24,7 @@ object TupleHelpers:
given singleSearch[H, Tail <: Tuple, K, TailOut <: Tuple](using
next: Subset[Tail, K *: EmptyTuple] { type Out = TailOut }
): Subset[H *: Tail, K *: EmptyTuple] with
type Out = H *: TailOut
type Out = Simplify[H *: TailOut]

type Remover[T <: Tuple, ToRemoveElement] = RemoverAll[T, ToRemoveElement *: EmptyTuple]

Expand Down Expand Up @@ -62,22 +62,27 @@ object TupleHelpers:
// We capture 'TailOut' as a type parameter to ensure it is fully resolved
given singleSearch[H, Tail <: Tuple, K, TailOut <: Tuple](using
next: RemoverAll.Aux[Tail, K *: EmptyTuple, TailOut]
): RemoverAll.Aux[H *: Tail, K *: EmptyTuple, H *: TailOut] =
new RemoverAll[H *: Tail, K *: EmptyTuple] { type Out = H *: TailOut }
): RemoverAll.Aux[H *: Tail, K *: EmptyTuple, Simplify[H *: TailOut]] =
new RemoverAll[H *: Tail, K *: EmptyTuple] { type Out = Simplify[H *: TailOut] }

// Simplify tuple types to avoid ugly type signatures like "X *: EmptyTuple.type"
type Simplify[T <: Tuple] <: Tuple = T match
case h *: EmptyTuple => Tuple1[h]
case _ => T

trait Replacer[T <: Tuple, Target, Replacement]:
type Out <: Tuple

object Replacer extends ReplacerLowPriority:

given found[Target, Tail <: Tuple, Replacement]: Replacer[Target *: Tail, Target, Replacement] with
type Out = Replacement *: Tail
type Out = Simplify[Replacement *: Tail]

trait ReplacerLowPriority:
given recurse[Head, Tail <: Tuple, Target, Replacement, TailOut <: Tuple](using
next: Replacer[Tail, Target, Replacement] { type Out = TailOut }
): Replacer[Head *: Tail, Target, Replacement] with
type Out = Head *: TailOut
type Out = Simplify[Head *: TailOut]


import shapeful.Prime
Expand All @@ -96,8 +101,8 @@ object TupleHelpers:
/** If nothing found, we can't proof Member (e.g. for generics), just assume they are different. */
given assumeAbsent[Fixed <: Tuple, H, T <: Tuple, TailOut <: Tuple](using
tail: PrimeRest.Aux[Fixed, T, TailOut],
): PrimeRest.Aux[Fixed, H *: T, H *: TailOut] =
new PrimeRest[Fixed, H *: T] { type Out = H *: TailOut }
): PrimeRest.Aux[Fixed, H *: T, Simplify[H *: TailOut]] =
new PrimeRest[Fixed, H *: T] { type Out = Simplify[H *: TailOut] }


object PrimeRest extends PrimeRestLowPriority:
Expand All @@ -110,14 +115,14 @@ object TupleHelpers:
given present[Fixed <: Tuple, H, T <: Tuple, TailOut <: Tuple](using
ev: Member[H, Fixed] =:= true,
tail: PrimeRest.Aux[Fixed, T, TailOut],
): PrimeRest.Aux[Fixed, H *: T, Prime[H] *: TailOut] =
new PrimeRest[Fixed, H *: T] { type Out = Prime[H] *: TailOut }
): PrimeRest.Aux[Fixed, H *: T, Simplify[Prime[H] *: TailOut]] =
new PrimeRest[Fixed, H *: T] { type Out = Simplify[Prime[H] *: TailOut] }

given absent[Fixed <: Tuple, H, T <: Tuple, TailOut <: Tuple](using
ev: Member[H, Fixed] =:= false,
tail: PrimeRest.Aux[Fixed, T, TailOut],
): PrimeRest.Aux[Fixed, H *: T, H *: TailOut] =
new PrimeRest[Fixed, H *: T] { type Out = H *: TailOut }
): PrimeRest.Aux[Fixed, H *: T, Simplify[H *: TailOut]] =
new PrimeRest[Fixed, H *: T] { type Out = Simplify[H *: TailOut] }

trait PrimeConcat[R1 <: Tuple, R2 <: Tuple]:
type Out <: Tuple
Expand Down