some unification of scaltype determination

Author: lkdvos

src/indexnotation/instantiators.jl

@@ -124,12 +124,9 @@ function instantiate_generaltensor(
     if alloc ∈ (NewTensor, TemporaryTensor)
         TC = gensym("T_" * string(dst))
         istemporary = Val(alloc === TemporaryTensor)
-        if scaltype === nothing
-            TCval = α === One() ? instantiate_scalartype(src) :
-                instantiate_scalartype(Expr(:call, :*, α, src))
-        else
-            TCval = scaltype
-        end
+        TCval = @something(
+            scaltype, instantiate_scalartype(α === One() ? src : Expr(:call, :*, α, src))
+        )
         push!(out.args, Expr(:(=), TC, TCval))
         push!(
             out.args,
@@ -275,18 +272,15 @@ function instantiate_contraction(
     end
     if alloc ∈ (NewTensor, TemporaryTensor)
         TCsym = gensym("T_" * string(dst))
-        if scaltype === nothing
-            Atype = instantiate_scalartype(A)
-            Btype = instantiate_scalartype(B)
-            TCval = Expr(:call, :promote_contract, Atype, Btype)
-            if α !== One()
-                TCval = Expr(
-                    :call, :(Base.promote_op), :*, instantiate_scalartype(α), TCval
-                )
+        TCval = @something(
+            scaltype,
+            begin
+                TA = instantiate_scalartype(A)
+                TB = instantiate_scalartype(B)
+                TAB = :(promote_contract($TA, $TB))
+                α === One() ? TAB : :(Base.promote_op(*, $(instantiate_scalartype(α)), $TAB))
             end
-        else
-            TCval = scaltype
-        end
+        )
         istemporary = Val(alloc === TemporaryTensor)
         initC = Expr(
             :block, Expr(:(=), TCsym, TCval),