Algebraic data types: Difference between revisions

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=={{header|Nim}}==

<lang nim>import fusion/matching

{.experimental: "caseStmtMacros".}

type

Colour = enum Empty, Red, Black

left, right: RBTree[T]

value: T

proc `[]`[T](r: RBTree[T], idx: static[FieldIndex]): auto =

## enables tuple syntax for unpacking and matching

elif idx == 2: r.value

elif idx == 3: r.right

template B[T](l: untyped, v: T, r): RBTree[T] =

RBTree[T](colour: Black, left: l, value: v, right: r)

template R[T](l: untyped, v: T, r): RBTree[T] =

RBTree[T](colour: Red, left: l, value: v, right: r)

(Black, @a, @x, (Red, @b, @y, (Red, @c, @z, @d))):

t = R(B(a, x, b), y, B(c, z, d))

proc balance*[T](t: var RBTree[T]) = balImpl[T](t)

of (value: > x): t.left.ins(x); t.balance()

of (value: < x): t.right.ins(x); t.balance()

proc insert*[T](tt: var RBTree[T], xx: T) =

proc ins(t: var RBTree[T], x: T) = insImpl[T](t, x)