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3887 :: Term rewriting template for the proc definitions

• cdome (orginal) [2018-06-05T01:19:24+02:00] view original

  Hi,

  Is there a way to define a term rewriting template that will match proc definitions? Something like:

  template procRewrite{a}(a: untyped{nkProcDef}): untyped =
    a
  Run

  Can't make it to work easily. It needs to accept proc definition as untyped argument.

  Thanks a lot

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• Araq (orginal) [2018-06-05T17:08:33+02:00] view original

  I don't think this is possible. But where is the benefit over proc foo() {.mymacro.}?

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• cdome (orginal) [2018-06-06T00:33:49+02:00] view original

  Thanks for reply, The effect is exactly the same as you say. The only difference is that you don't need to annotate every function.

  I think it would be useful for test coverage library for example.

  Would you consider a PR?

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• Araq (orginal) [2018-06-06T11:40:26+02:00] view original

  I don't think so, if you want to apply it for multiple/all procs use the block syntax:

  transform:
    proc p() = discard
    proc q() = discard
  Run

  I know the additional indentation is annoying but {.push transform.} ... {.pop.} is worse IMO.

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• Udiknedormin (orginal) [2018-06-12T10:42:18+02:00] view original

  Well, actually, block syntax is one of the main reasons why I'm not really that enthusiastic about contract library for Nim as you need to either annotate pretty much every piece of code, or indent the whole module, neither of which sounds like fun to me. :-/

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• Lando (orginal) [2018-06-12T17:42:33+02:00] view original

  or indent the whole module

  I would like a reserved identifier for a macro which I can optionally implement and which is automatically invoked with the entire module's AST as its argument.

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• mratsim (orginal) [2018-06-12T18:33:56+02:00] view original

  I thought Nim supported "Higher-Level-Module" like higher level function?

  fooMacro:
    ./path/to/module
  Run

  Also there is the fresh out the oven compiler API, not sure if it can be use for that.

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• Lando (orginal) [2018-06-14T22:56:03+02:00] view original

  Hmm, couldn't get the "higher-order-module" solution to work, but a simple include seems to do the trick:

  # main module:
  import macros
  
  macro mangleModule(modl: typed): untyped =
    echo modl.treeRepr
    result = modl[0].last
    result.last.last[0].strVal = "Ho"
  
  mangleModule:
    include test
  
  # module test:
  echo "Hi"
  
  # output:
  StmtList
    StmtList
      IncludeStmt
        Ident "test"
      Command
        Sym "echo"
        HiddenStdConv
          Empty
          Bracket
            StrLit "Hi"
  
  ...
  
  Ho
  Run

  The typed version of the AST of the include statement apparently consists of the statement itself followed by the AST of the included code. Strange, but useful :).

  As to the compiler API (looked at nimeval.nim): one would have to inject a macro call as the first statement of the interpreted script, I don't see how to do that.

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