Conform stream.map to FL spec and clarify stream internal properties (#…

…2481)

* Conform stream.map to FL spec. Clarify stream internal properties.

* Streamline ignoreInitial logic, code style edit

stream/stream.js

@@ -27,8 +27,8 @@ function Stream(value) {
 		if (arguments.length && v !== Stream.SKIP) {
 			value = v
 			if (open(stream)) {
-				stream.changing()
-				stream.state = "active"
+				stream._changing()
+				stream._state = "active"
 				dependentStreams.forEach(function(s, i) { s(dependentFns[i](value)) })
 			}
 		}
@@ -37,35 +37,36 @@ function Stream(value) {
 	}
 
 	stream.constructor = Stream
-	stream.state = arguments.length && value !== Stream.SKIP ? "active" : "pending"
-	stream.parents = []
+	stream._state = arguments.length && value !== Stream.SKIP ? "active" : "pending"
+	stream._parents = []
 
-	stream.changing = function() {
-		open(stream) && (stream.state = "changing")
+	stream._changing = function() {
+		if (open(stream)) stream._state = "changing"
 		dependentStreams.forEach(function(s) {
-			s.changing()
+			s._changing()
 		})
 	}
 
-	stream.map = function(fn, ignoreInitial) {
-		var target = stream.state === "active" && ignoreInitial !== Stream.SKIP
-			? Stream(fn(value))
-			: Stream()
-		target.parents.push(stream)
-
+	stream._map = function(fn, ignoreInitial) {
+		var target = ignoreInitial ? Stream() : Stream(fn(value))
+		target._parents.push(stream)
 		dependentStreams.push(target)
 		dependentFns.push(fn)
 		return target
 	}
 
+	stream.map = function(fn) {
+		return stream._map(fn, stream._state !== "active")
+	}
+
 	var end
 	function createEnd() {
 		end = Stream()
 		end.map(function(value) {
 			if (value === true) {
-				stream.parents.forEach(function (p) {p.unregisterChild(stream)})
-				stream.state = "ended"
-				stream.parents.length = dependentStreams.length = dependentFns.length = 0
+				stream._parents.forEach(function (p) {p._unregisterChild(stream)})
+				stream._state = "ended"
+				stream._parents.length = dependentStreams.length = dependentFns.length = 0
 			}
 			return value
 		})
@@ -77,7 +78,7 @@ function Stream(value) {
 	stream["fantasy-land/map"] = stream.map
 	stream["fantasy-land/ap"] = function(x) { return combine(function(s1, s2) { return s1()(s2()) }, [x, stream]) }
 
-	stream.unregisterChild = function(child) {
+	stream._unregisterChild = function(child) {
 		var childIndex = dependentStreams.indexOf(child)
 		if (childIndex !== -1) {
 			dependentStreams.splice(childIndex, 1)
@@ -96,7 +97,7 @@ function combine(fn, streams) {
 	var ready = streams.every(function(s) {
 		if (s.constructor !== Stream)
 			throw new Error("Ensure that each item passed to stream.combine/stream.merge/lift is a stream")
-		return s.state === "active"
+		return s._state === "active"
 	})
 	var stream = ready
 		? Stream(fn.apply(null, streams.concat([streams])))
@@ -105,15 +106,15 @@ function combine(fn, streams) {
 	var changed = []
 
 	var mappers = streams.map(function(s) {
-		return s.map(function(value) {
+		return s._map(function(value) {
 			changed.push(s)
-			if (ready || streams.every(function(s) { return s.state !== "pending" })) {
+			if (ready || streams.every(function(s) { return s._state !== "pending" })) {
 				ready = true
 				stream(fn.apply(null, streams.concat([changed])))
 				changed = []
 			}
 			return value
-		}, Stream.SKIP)
+		}, true)
 	})
 
 	var endStream = stream.end.map(function(value) {
@@ -168,7 +169,7 @@ function lift() {
 }
 
 function open(s) {
-	return s.state === "pending" || s.state === "active" || s.state === "changing"
+	return s._state === "pending" || s._state === "active" || s._state === "changing"
 }
 
 if (typeof module !== "undefined") module["exports"] = Stream