Nim/tests/macros/tmacrogenerics.nim

discard """
  file: "tmacrogenerics.nim"
  msg: '''
instantiation 1 with typedesc and typedesc
counter: 1
'''
  output: "int\nfloat\nint\nstring"
"""

import typetraits, macros

var counter {.compileTime.} = 0

macro makeBar(A, B: typedesc): typedesc =
  inc counter
  echo "instantiation ", counter, " with ", A.name, " and ", B.name
  result = A

type
  Bar[T, U] = makeBar(T, U)

var bb1: Bar[int, float]
var bb2: Bar[float, string]
var bb3: Bar[int, float]
var bb4: Bar[string, string]

proc match(a: int)    = echo "int"
proc match(a: string) = echo "string"
proc match(a: float)  = echo "float"

match(bb1)
match(bb2)
match(bb3)
match(bb4)

static:
  echo "counter: ", counter