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1361 :: SOLVED: The result of `repr` is not expected.

• lijie (orginal) [2015-06-24T18:17:53+02:00] view original

  There are two pieces of code.

  
  import macros
  
  macro foo(): stmt =
    result = quote do:
      let foofoo = not true
    echo treeRepr(result)
    echo repr(result)
  
  foo()
  Run

  Outputs:

  
  StmtList
    LetSection
      IdentDefs
        Sym "foofoo"
        Empty
        Prefix
          OpenSymChoice
            Sym "not"
            Sym "not"
            Sym "not"
            Sym "not"
            Sym "not"
            Sym "not"
          Sym "true"
    
    let foofoo = (system.not|system.not|system.not|system.not|system.not|system.not|...) true
  Run

  And

  
  import macros, tables
  
  macro bar(): stmt =
    result = quote do:
      var a = initTable[int, int]();
      let b = a.hasKey(1)
    echo treeRepr(result)
    echo repr(result)
  
  bar()
  Run

  Outputs:

  
  StmtList
    VarSection
      IdentDefs
        Sym "a"
        Empty
        Call
          BracketExpr
            Sym "initTable"
            Sym "int"
            Sym "int"
    LetSection
      IdentDefs
        Sym "b"
        Empty
        Call
          DotExpr
            Sym "a"
            OpenSymChoice
              Sym "hasKey"
              Sym "hasKey"
              Sym "hasKey"
              Sym "hasKey"
              Sym "hasKey"
              Sym "hasKey"
          IntLit 1
    
    var a = initTable[int, int]()
    let b = a.(tables.hasKey|tables.hasKey|tables.hasKey|tables.hasKey|tables.hasKey|tables.hasKey|...)(
        1)
  Run

  Why are there so many not and hasKey, it should only one.

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• Jehan (orginal) [2015-06-24T20:09:43+02:00] view original

  Because not and hasKey are overloaded and haven't been resolved yet. Overloading resolution does not occur until the macro result is evaluated by the compiler, because in general that's impossible without the context in which it exists. While in this particular example, overloading could in theory be resolved earlier, the compiler does not know that.

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• lijie (orginal) [2015-06-25T18:01:03+02:00] view original

  OK, I understand.

  Thanks.

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