asynce.nim

import macros

macro awaitE(call: typed, r: untyped): untyped =
  let x = call[0]

  let tx = x.getType()
  expectKind tx, nnkBracketExpr
  var t = newTree(nnkProcTy)
  var p = newTree(nnkFormalParams, tx[1])
  for i in 2 ..< tx.len:
    p.add newIdentDefs(ident("param" & $(i-1)), tx[i], newEmptyNode())

  t.add p
  t.add newTree(nnkPragma, ident("nimcall"), newTree(nnkExprColonExpr, ident"raises", r))

  echo repr t

  template check(t, x) = discard [t(x)]

  result = newTree(nnkStmtListExpr, getAst(check(t, x)), call)

proc baz(x: int) = raise newException(IOError, "test")

awaitE baz(3), [OSError]