DI by macro

CodeWrapperSample.nim

import macros, sugar, sequtils
import rationals

proc `//`[T: SomeInteger](num, den: T): Rational[T] = initRational(num, den)
proc `//`[T: not SomeInteger](num, den: T): auto = num / den

proc genReplacer(fromNode, toNode: NimNode): auto =
    proc replacer(node: NimNode):NimNode =
        if node.len == 0:
            if node.kind == nnkIdent and node == fromNode:
                return toNode
            else:
                return node
        let newNode = copyNimNode(node)
        newNode.add node.mapIt(replacer(it))
        return newNode
    return replacer

macro Rational(field: untyped):untyped = genReplacer(ident"/", ident"//")(field)

block:
    echo 1 / 2
    echo 1.0 / 2.0

Rational:
    echo 1 / 2
    echo 1.0 / 2.0