Pretty-printing --print ast/js-ast

[xkxx]

A minor thing I found previously: if you use pr-str instead of JSON.stringify to process the debug output, it looks much nicer:

> echo "(print x)" | ./bin/wisp.js --compile --print ast
[{"op" "invoke",
    "callee" {"start" {"line" 0,
                       "column" 0},
              "end" {"line" 0,
                     "column" 9},
              "op" "member-expression",
              "computed" false,
              "form" (aget console (quote log)),
              "target" {"start" {"line" 0,
                                 "column" 0},
                        "end" {"line" 0,
                               "column" 8},
                        "op" "var",
                        "type" "identifier",
                        "form" console,
                        "binding" {"op" "unresolved-binding",
                                   "type" "unresolved-binding",
                                   "identifier" {"type" "identifier",
                                                 "form" console},
                                   "start" {"line" 0,
                                            "column" 0},
                                   "end" {"line" 0,
                                          "column" 8}}},
              "property" {"start" {"line" 0,
                                   "column" 8},
                          "end" {"line" 0,
                                 "column" 9},
                          "op" "var",
                          "type" "identifier",
                          "form" log,
                          "binding" nil}},
    "params" [{"start" {"line" 0,
                        "column" 7},
               "end" {"line" 0,
                      "column" 8},
               "op" "var",
               "type" "identifier",
               "form" x,
               "binding" {"op" "unresolved-binding",
                          "type" "unresolved-binding",
                          "identifier" {"type" "identifier",
                                        "form" x},
                          "start" {"line" 0,
                                   "column" 7},
                          "end" {"line" 0,
                                 "column" 8}}}],
    "form" (console.log x)}]

vs.

> echo "(print x)" | ./bin/wisp.js --compile --print ast
[
  {
    "op": "invoke",
    "callee": {
      "start": {
        "line": 0,
        "column": 0
      },
      "end": {
        "line": 0,
        "column": 9
      },
      "op": "member-expression",
      "computed": false,
      "form": {
        "head": {
          "name": "aget"
        },
        "tail": {
          "head": {
            "name": "console"
          },
          "tail": {
            "head": {
              "head": {
                "name": "quote"
              },
              "tail": {
                "head": {
                  "name": "log"
                },
                "tail": {},
                "length": 1
              },
              "length": 2
            },
            "tail": {},
            "length": 1
          },
          "length": 2
        },
        "length": 3
      },
      "target": {
        "start": {
          "line": 0,
          "column": 0
        },
        "end": {
          "line": 0,
          "column": 8
        },
        "op": "var",
        "type": "identifier",
        "form": {
          "name": "console"
        },
        "binding": {
          "op": "unresolved-binding",
          "type": "unresolved-binding",
          "identifier": {
            "type": "identifier",
            "form": {
              "name": "console"
            }
          },
          "start": {
            "line": 0,
            "column": 0
          },
          "end": {
            "line": 0,
            "column": 8
          }
        }
      },
      "property": {
        "start": {
          "line": 0,
          "column": 8
        },
        "end": {
          "line": 0,
          "column": 9
        },
        "op": "var",
        "type": "identifier",
        "form": {
          "name": "log"
        }
      }
    },
    "params": [
      {
        "start": {
          "line": 0,
          "column": 7
        },
        "end": {
          "line": 0,
          "column": 8
        },
        "op": "var",
        "type": "identifier",
        "form": {
          "name": "x"
        },
        "binding": {
          "op": "unresolved-binding",
          "type": "unresolved-binding",
          "identifier": {
            "type": "identifier",
            "form": {
              "name": "x"
            }
          },
          "start": {
            "line": 0,
            "column": 7
          },
          "end": {
            "line": 0,
            "column": 8
          }
        }
      }
    ],
    "form": {
      "head": {
        "name": "console.log"
      },
      "tail": {
        "head": {
          "name": "x"
        },
        "tail": {},
        "length": 1
      },
      "length": 2
    }
  }
]

Coffeescript does something similar:

> coffee -cep -n "print x"
Block
  Call
    Value "print"
    Value "x"

I did talk about this in my last pull request, but that thread was too convoluted as-is.