Fail.

chapter1/reader.coffee

@@ -1,13 +1,19 @@
 {car, cdr, cons, nil, nilp, pairp, vectorToList, list} = require 'cons-lists/lists'
+{length} = require 'cons-lists/reduce'
 {inspect} = require "util"
 
-
 NEWLINES   = ["\n", "\r", "\x0B", "\x0C"]
 WHITESPACE = [" ", "\t"].concat(NEWLINES)
 
 EOF = new (class Eof)()
 EOO = new (class Eoo)()
 
+stringp = (o) -> o?.__type == 'string'
+
+errorp = (o) -> (pairp o) and (car o) == 'error'
+
+streq = (s, t) -> String(s) == String(t)
+
 class Source
   constructor: (@inStream) ->
     @index = 0
@@ -32,13 +38,24 @@ class Source
 skipWS = (inStream) ->
   while inStream.peek() in WHITESPACE then inStream.next()
 
+invisibleProperty = (obj, name, value) ->
+  Object.defineProperty obj, name,
+    value: value
+    configurable: false
+    enumerable: false
+    writable: false
+  obj
+
+lineInfo = (obj, line, column) ->
+  invisibleProperty obj, '__position', {line: line, column: column}
+
 # (type, value, line, column) -> (node {type, value, line, column)}
-makeObj = (type, value, line, column) ->
-  list(type, value, line, column)
+makeObj = (value, type, line, column) ->
+  lineInfo (invisibleProperty value, '__type', type), line, column
 
 # msg -> (IO -> Node => Error)
 handleError = (message) ->
-  (line, column) -> makeObj('error', message, line, column)
+  (line, column) -> lineInfo (cons "error", message), line, column
 
 # IO -> Node => Comment
 readComment = (inStream) ->
@@ -47,26 +64,26 @@ readComment = (inStream) ->
     inStream.next()).join("")
   if not inStream.done()
     inStream.next()
-  makeObj 'comment', r, line, column
+  makeObj (new String r), 'comment', line, column
 
 # IO -> (Node => Literal => String) | Error
 readString = (inStream) ->
   [line, column] = inStream.position()
   inStream.next()
-  string = until inStream.peek() == '"' or inStream.done()
-    if inStream.peek() == '\\'
+  string = until streq(inStream.peek(), '"') or inStream.done()
+    if (streq inStream.peek(), '\\')
       inStream.next()
     inStream.next()
   if inStream.done()
     return handleError("end of file seen before end of string.")(line, column)
   inStream.next()
-  makeObj 'string', (string.join ''), line, column
+  makeObj (new String (string.join '')), 'string', line, column
 
 # (String) -> (Node => Literal => Number) | Nothing
 readMaybeNumber = (symbol) ->
-  if symbol[0] == '+'
+  if streq(symbol[0], '+')
     return readMaybeNumber symbol.substr(1)
-  if symbol[0] == '-'
+  if streq(symbol[0], '-')
     ret = readMaybeNumber symbol.substr(1)
     return if ret? then -1 * ret else undefined
   if symbol.search(/^0x[0-9a-fA-F]+$/) > -1
@@ -85,43 +102,48 @@ readSymbol = (inStream, tableKeys) ->
   symbol = (until (inStream.done() or inStream.peek() in tableKeys or inStream.peek() in WHITESPACE)
     inStream.next()).join ''
   number = readMaybeNumber symbol
+  if nilp number
+    return nil
   if number?
-    return makeObj 'number', number, line, column
-  makeObj 'symbol', symbol, line, column
+    return makeObj (new Number number), 'number', line, column
+  makeObj (new String symbol), 'symbol', line, column
 
 
 # (Delim, TypeName) -> IO -> (IO, node) | Error
-makeReadPair = (delim, type) ->
+makeReadContainer = (delim, constructor) ->
   # IO -> (IO, Node) | Error
   (inStream) ->
     inStream.next()
     skipWS inStream
     [line, column] = inStream.position()
-    if inStream.peek() == delim
+    if streq(inStream.peek(), delim)
       inStream.next()
-      return makeObj(type, nil, line, column)
+      return constructor(nil, line, column)
 
     # IO -> (IO, Node) | Error
     dotted = false
-    readEachPair = (inStream) ->
+    readInContainer = (inStream) ->
       [line, column] = inStream.position()
       obj = read inStream, true, null, true
-      if inStream.peek() == delim
+      if streq(inStream.peek(), delim)
         if dotted then return obj
-        return cons obj, nil
+        return lineInfo (cons obj, nil), line, column
       if inStream.done() then return handleError("Unexpected end of input")(line, column)
       if dotted then return handleError("More than one symbol after dot")
-      return obj if (car obj) == 'error'
-      if (car obj) == 'symbol' and (car cdr obj) == '.'
+      return obj if (errorp obj)
+      if streq(obj, ".")
         dotted = true
-        return readEachPair inStream
-      cons obj, readEachPair inStream
+        return readInContainer inStream
+      cons obj, readInContainer inStream
 
-    ret = makeObj type, readEachPair(inStream), line, column
+    ret = readInContainer(inStream)
     inStream.next()
     ret
 
 # Type -> (IO -> (IO, Node))
+#
+# Handles the quoted symbol things.
+#
 prefixReader = (type) ->
   # IO -> (IO, Node)
   (inStream) ->
@@ -130,7 +152,7 @@ prefixReader = (type) ->
     [line1, column1] = inStream.position()
     obj = read inStream, true, null, true
     return obj if (car obj) == 'error'
-    makeObj "list", cons((makeObj("symbol", type, line1, column1)), cons(obj)), line, column
+    cons (makeObj (new String type), 'symbol', line1, column1), obj
 
 # I really wanted to make anything more complex than a list (like an
 # object or a vector) something handled by a read macro.  Maybe in a
@@ -138,12 +160,14 @@ prefixReader = (type) ->
 
 readMacros =
   '"': readString
-  '(': makeReadPair ')', 'list'
+  '(': makeReadContainer ')', (o, l, c) -> lineInfo o, l, c
   ')': handleError "Closing paren encountered"
-  '[': makeReadPair ']', 'vector'
+  '[': makeReadContainer ']', (o, l, c) -> cons("vector", lineinfo o, l, c)
   ']': handleError "Closing bracket encountered"
-  '{': makeReadPair('}', 'record', (res) ->
-    res.length % 2 == 0 and true or mkerr "record key without value")
+  '{': makeReadContainer '}', (o, l, c) ->
+    if length(o) % 2 != 0
+      return handleError "Records require an even number of items."
+    cons('record', lineinfo o, l, c)
   '}': handleError "Closing curly without corresponding opening."
   "`": prefixReader 'back-quote'
   "'": prefixReader 'quote'
@@ -153,9 +177,9 @@ readMacros =
 
 # Given a stream, reads from the stream until a single complete lisp
 # object has been found and returns the object
-
 # IO -> Form
-read = (inStream, eofErrorP = false, eofError = EOF, recursiveP = false, inReadMacros = null, keepComments = false) ->
+read = (inStream, eofErrorP = false, eofError = EOF,
+        recursiveP = false, inReadMacros = null, keepComments = false) ->
   inStream = if inStream instanceof Source then inStream else new Source inStream
   inReadMacros = if InReadMacros? then inReadMacros else readMacros
   inReadMacroKeys = (i for i of inReadMacros)