Array traits addDelegate: #parent2 valued: Sequence traits.
"Ensures that the primitive Array type has the behaviors and features of a
Sequence."

a@(Array traits) copy
[
  a clone
].

a@(Array traits) printOn: s
[
  s nextPut: ${.
  a do: [| :each | each printOn: s] separatedBy: [s ; '. '].
  s nextPut: $}.
  a
].

ByteArray traits addDelegate: #parent2 valued: Sequence traits.
"Ensures that the primitive ByteArray type has the behaviors and features of
a Sequence."

a@(ByteArray traits) copy
[
  a clone
].

a@(ByteArray traits) printOn: s
[
  s nextPut: ${.
  a do: [| :each | each printOn: s] separatedBy: [s ; '. '].
  s nextPut: $}.
  a
].

b@(ByteArray traits) as: a@(Array traits)
"Converts the integer codes into character objects."
[| result |
  result: (a newSizeOf: b).
  b doWithIndex: [| :each :index | result at: index put: (each as: Character)].
  result
].

a@(Array traits) as: b@(ByteArray traits)
"Converts the integer codes into character objects; this also replaces Nil's
with zero-code characters."
[| result |
  result: (b newSizeOf: a).
  a doWithIndex: [| :each :index |
		  each ifNil: [result at: index put: 0]
		       ifNotNil: [result at: index put: (each as: Integer)]].
  result
].

s@(String traits) as: b@(ByteArray traits)
"Converts the character objects into their integer codes."
[| result |
  result: (b newSizeOf: s).
  s doWithIndex: [| :each :index | result at: index put: (each as: Integer)].
  result
].

b@(ByteArray traits) as: s@(String traits)
"Converts the integer codes into character objects."
[| result |
  result: (s newSizeOf: b).
  b doWithIndex: [| :each :index | result at: index put: (each as: Character)].
  result
].

collections addSlot: #NumericArray valued: Array derive.
NumericArray addDelegate: #Numeric valued: NumericMixin.

collections addSlot: #ArrayMD valued: Collection derive.
"Multi-dimensional arrays don't readily admit to sequencing or mutation."

ArrayMD addSlot: #dimensions valued: {1}.
"Default is a scalar: one dimension, of extent 1."
ArrayMD addSlot: #contents valued: (Array newSize: 1).
"Store the contents in an array of exactly the right size."

mda@(ArrayMD traits) newEmpty
"Deprecated. Meant for compatibility with Collection methods that require
it, particularly select:-type methods. The alternative is to return a new
array of the same dimensions and sparsely populate it, but that's over-
complicated."
[
  Bag newEmpty
].

mda@(ArrayMD traits) newSize: _
"Deprecated. Meant for compatibility with Collection methods that require it.
It takes it's dimensions from the target array, so is not meant to be
called on the ArrayMD prototype itself."
[| newMDA |
  newMDA: mda clone.
  newMDA dimensions: mda dimensions.
  newMDA contents: (mda contents newSizeOf: mda).
  newMDA
].

mda@(ArrayMD traits) newWithDimensions: sc@(Sequence traits)
"Set up the array to hold enough elements as specified by an array or vector
of dimension sizes. Dimension size 0 is coerced to 1."
[| newMDA size |
  size: 1.
  sc do: [| :each | size: size * each ].
  newMDA: mda clone.
  newMDA contents: (mda contents newSize: size).
  newMDA dimensions: (sc collect: [| :each | each max: 1]).
  newMDA
].

mda@(ArrayMD traits) size
[
  mda contents size
].

mda@(ArrayMD traits) numDimensions
"Dimensions of size 0 or 1 don't introduce actual variations."
[
  mda dimensions count: [| :each | each > 1]
].

mda@(ArrayMD traits) at: n@(Integer traits)
"Return a slice of the mda using an index of the first dimension."
[
  
].

mda@(ArrayMD traits) indexOf: sc@(Sequence traits)
"Returns the place in the contents where the given sequence of coordinates
maps to. This should not be called repetitively, as it would duplicate
a lot of calculation."
[| final offset |
  sc size = mda dimensions size ifFalse: [mda notYetImplemented].
  final: 0.
  offset: 1.
  sc with: mda dimensions do: [| :index :dimSize |
    final: final + (index * offset).
    offset: offset * dimSize].
  final
].

mda@(ArrayMD traits) at: sc@(Sequence traits)
[
  mda contents at: (mda indexOf: sc)
].

mda@(ArrayMD traits) at: sc@(Sequence traits) put: obj
[
  mda contents at: (mda indexOf: sc) put: obj
].

mda@(ArrayMD traits) do: block
[
  mda contents do: block
].

mda@(ArrayMD traits) sliceAt: m in: n
"Return an array slice, defined by the array of all addresses having
value m in position n. This works lazily."
[
  MDArraySlice for: mda at: m in: n
].

mda@(ArrayMD traits) sliceAt: m in: n do: block
"Act on all elements having index m in dimension n, in order. This has
a dimension of one less than mda's."
[| firstIndex stepIndex |
  firstIndex: (mda indexOf:
    ((Array newSize: mda numDimensions) at: n put: m)).
  stepIndex: (mda dimensions inject: 1 into: [| :step :each |
    ]).
  firstIndex upTo: mda size - 1 by: stepIndex do: block.
].

collections addSlot: #MDArraySlice valued: Collection derive.
MDArraySlice addSlot: #array. "The source array."
MDArraySlice addSlot: #dimension. "Which dimension is the slice through?"
MDArraySlice addSlot: #start. "The starting index value."
MDArraySlice addSlot: #end. "The ending value, or Nil for thin slices."

as@(MDArraySlice traits) for: mda@(ArrayMD traits) at: m in: n
[| newSlice |
  n > mda numDimensions ifTrue: [^ Nil].
  m >= (mda dimensions at: n) ifTrue: [^ Nil].
  newSlice: as clone.
  newSlice array: mda.
  newSlice dimension: n.
  newSlice start: m.
  newSlice end: Nil.
  newSlice
].

as@(MDArraySlice traits) for: mda@(ArrayMD traits) from: m to: l in: n
[| newSlice |
  n > mda numDimensions ifTrue: [^ Nil].
  m >= (mda dimensions at: n) ifTrue: [^ Nil].
  newSlice: as clone.
  newSlice array: mda.
  newSlice dimension: n.
  newSlice start: (m min: l).
  newSlice end: (l max: m).
  newSlice
].



collections addSlot: #NumericArrayMD valued: ArrayMD derive.
NumericArrayMD contents: (NumericArray newSize: 1).

a1@(NumericArrayMD traits) + a2@(NumericArrayMD traits)
[| newMDA |
  a1 dimensions = a2 dimensions ifFalse: [Nil].
  newMDA: a1 clone.
  newMDA contents: a1 contents + a2 contents.
  newMDA
].

mda@(NumericArrayMD traits) negated
[| newMDA |
  newMDA: mda clone.
  newMDA contents: mda contents negated.
].

a1@(NumericArrayMD traits) - a2@(NumericArrayMD traits)
[
  a1 + a2 negated
].