diff --git a/lib/idris-controller.coffee b/lib/idris-controller.coffee
index b7348b1..3247a67 100644
--- a/lib/idris-controller.coffee
+++ b/lib/idris-controller.coffee
@@ -3,13 +3,16 @@ PlainMessageView = require('atom-message-panel').PlainMessageView
 LineMessageView = require('atom-message-panel').LineMessageView
 ProofObligationView = require('./proof-obligation-view')
 MetavariablesView = require './metavariables-view'
+SourceHighlightHelp = require('./utils/sourceHighlight.coffee')
 
 class IdrisController
   idrisBuffers: 0
   localChanges: undefined
 
+
   constructor: (@statusbar, @model) ->
     @idrisBuffers = 0
+    @semanticMarkers = []
 
     atom.workspace.getTextEditors().forEach (editor) =>
       uri = editor.getURI()
@@ -58,14 +61,14 @@ class IdrisController
     @messages.hide()
     @localChanges = false
     if @isIdrisFile(editor.getURI())
-      @loadFile editor.getURI()
+      @loadFile editor
 
   idrisFileChanged: (editor) ->
     @localChanges = editor.isModified()
     if @localChanges
       @statusbar.setStatus 'Idris: local modifications'
     else if @isIdrisFile(editor.getURI())
-      @loadFile editor.getURI()
+      @loadFile editor
 
   idrisFileClosed: (editor) ->
     @idrisBuffers -= 1
@@ -81,7 +84,7 @@ class IdrisController
       uri = editor.getPath()
       if @isIdrisFile(uri)
         @statusbar.show()
-        @loadFile uri
+        @loadFile editor
       else
         @statusbar.hide()
 
@@ -96,10 +99,18 @@ class IdrisController
     cursorPosition = editor.getLastCursor().getCurrentWordBufferRange()
     editor.getTextInBufferRange cursorPosition
 
-  loadFile: (uri) ->
+  loadFile: (editor) ->
+    console.log editor
+    uri = editor.getURI()
     console.log 'Loading ' + uri
     @messages.clear()
-    @model.load uri, (err, message, progress) =>
+
+    console.log @semanticMarkers
+    for marker in @semanticMarkers
+      marker.destroy()
+    @semanticMarkers = []
+
+    callback = (err, message, progress) =>
       if err
         @statusbar.setStatus 'Idris: ' + err.message
         @messages.show()
@@ -115,6 +126,19 @@ class IdrisController
         @statusbar.setStatus 'Idris: ' + progress
       else
         @statusbar.setStatus 'Idris: ' + JSON.stringify(message)
+    @model.load uri, callback, (highlightMsg) =>
+      if atom.config.get('language-idris.semanticHighlighting') && highlightMsg && highlightMsg[0] == ":highlight-source"
+        for [where, what] in highlightMsg[1]
+          {file, start, end} = SourceHighlightHelp.fileLocation(where)
+          semanticClass = SourceHighlightHelp.decoClass(what)
+          if file == editor.getPath()
+            marker = editor.markBufferRange([start, end],
+                                            invalidate: 'never')
+            decoration = editor.decorateMarker(marker,
+                                               type: "highlight",
+                                               class: semanticClass)
+            @semanticMarkers.push(marker)
+
 
   getDocsForWord: ({target}) =>
     word = @getWordUnderCursor target
diff --git a/lib/idris-model.coffee b/lib/idris-model.coffee
index 608547a..36c85c5 100644
--- a/lib/idris-model.coffee
+++ b/lib/idris-model.coffee
@@ -10,6 +10,7 @@ class IdrisModel extends EventEmitter
     @buffer = ''
     @process = undefined
     @callbacks = {}
+    @outputCallbacks = {}
     @warnings = {}
     super this
 
@@ -77,12 +78,18 @@ class IdrisModel extends EventEmitter
                 message: ret[1]
                 warnings: @warnings[id]
             delete @callbacks[id]
+            #delete @outputCallbacks[id]
             delete @warnings[id]
         when ':write-string'
           id = params[params.length - 1]
           msg = params[0]
           if @callbacks[id]
             @callbacks[id] undefined, undefined, msg
+        when ':output'
+          id = params[params.length - 1]
+          msg = params[0]
+          if @outputCallbacks[id] && msg[0] == ':ok'
+            @outputCallbacks[id] msg[1]
         when ':warning'
           id = params[params.length - 1]
           warning = params[0]
@@ -105,14 +112,16 @@ class IdrisModel extends EventEmitter
     Logger.logOutgoingCommand cmd
     @process.stdin.write sexpFormatter.serialize(cmd)
 
-  prepareCommand: (cmd, callback) ->
+  prepareCommand: (cmd, callback, outputCallback = null) ->
     id = @getUID()
     @callbacks[id] = callback
+    if outputCallback
+      @outputCallbacks[id] = outputCallback
     @warnings[id] = []
     @sendCommand [cmd, id]
 
-  load: (uri, callback) ->
-    @prepareCommand [':load-file', uri], callback
+  load: (uri, callback, outputCallback) ->
+    @prepareCommand [':load-file', uri], callback, outputCallback
 
   docsFor: (word, callback) ->
     @prepareCommand [':docs-for', word], callback
diff --git a/lib/language-idris.coffee b/lib/language-idris.coffee
index e0be3ab..0b26a68 100644
--- a/lib/language-idris.coffee
+++ b/lib/language-idris.coffee
@@ -10,6 +10,9 @@ module.exports =
     pathToIdris:
       type: 'string'
       default: 'idris'
+    semanticHighlighting:
+      type: 'boolean'
+      default: false
 
   activate: ->
     pathToIdris = atom.config.get "language-idris.pathToIdris"
diff --git a/lib/utils/sourceHighlight.coffee b/lib/utils/sourceHighlight.coffee
new file mode 100644
index 0000000..dd07e89
--- /dev/null
+++ b/lib/utils/sourceHighlight.coffee
@@ -0,0 +1,36 @@
+fileLocation = (where) ->
+  [[tag1, file], [tag2, startLine, startCol], [tag3, endLine, endCol]] = where
+  if tag1 == ':filename' && tag2 == ':start' && tag3 == ':end'
+    {file: file, start: [startLine - 1, startCol - 1], end: [endLine - 1 , endCol - 1]}
+  else
+    throw ("bad location " + where)
+
+assoc = (key, list) ->
+  try
+    [car, cdr...] = list
+    [k, vs...] = car
+    if k == key
+      vs
+    else
+      assoc key, cdr
+  catch e
+    null
+
+
+decoClass = (props) ->
+  decor = assoc ':decor', props
+  console.log decor
+  decoClass =
+    switch decor[0]
+      when ':function' then ' function'
+      when ':bound'    then ' bound'
+      when ':data'     then ' data'
+      when ':metavar'  then ' metavar'
+      when ':type'     then ' type'
+      else ''
+  console.log decoClass
+  'idris-thing' + decoClass
+
+module.exports =
+  fileLocation: fileLocation
+  decoClass: decoClass
diff --git a/package.json b/package.json
index bb6c1db..ee7216b 100644
--- a/package.json
+++ b/package.json
@@ -21,6 +21,10 @@
     {
       "name": "Heather",
       "url": "https://github.com/Heather"
+    },
+    {
+      "name": "David Christiansen",
+      "url": "http://www.davidchristiansen.dk"
     }
   ],
   "consumedServices": {
diff --git a/styles/idris.atom-text-editor.less b/styles/idris.atom-text-editor.less
new file mode 100644
index 0000000..1914585
--- /dev/null
+++ b/styles/idris.atom-text-editor.less
@@ -0,0 +1,25 @@
+.editor .idris-thing .region {
+
+}
+
+.editor .idris-thing.type .region {
+  background-color: #EBFAFF;
+}
+
+.editor .idris-thing.function .region {
+  background-color: #B2F0B2;
+}
+
+.editor .idris-thing.bound .region {
+  background-color: #D9B2D9;
+}
+.editor .idris-thing.metavar .region {
+  border: 1px solid gray !important;
+}
+
+.editor .idris-thing.data .region {
+  background-color: #FF9999;
+}
+
+.editor .idris-thing.module .region {
+}
diff --git a/styles/idris.atom-text-editor.less~ b/styles/idris.atom-text-editor.less~
new file mode 100644
index 0000000..0072292
--- /dev/null
+++ b/styles/idris.atom-text-editor.less~
@@ -0,0 +1,3 @@
+.HERE .region {
+  color: red;
+}