diff --git a/src/Main.hs b/src/Main.hs
index d989b11..8f1d49f 100644
--- a/src/Main.hs
+++ b/src/Main.hs
@@ -7,7 +7,37 @@ module Main (main) where
 
 import Relude
 
+import Types
+
 -- MAIN --
 
 main :: IO ()
-main = putTextLn "hallo Welt"
+main = do
+  putTextLn "hallo Welt"
+  putStrLn $ generateGLSL vertShader
+  putStrLn $ generateGLSL fragShader
+
+fragShader :: Program
+fragShader =
+  [ VersionDeclaration 450 Core
+  , VariableDeclaration Nothing In fragColorIn
+  , VariableDeclaration Nothing Out fragColorOut
+  , MainStart
+  , VariableAssignment fragColorOut fragColorIn
+  ]
+
+vertShader :: Program
+vertShader =
+  [ VersionDeclaration 450 Core
+  , VariableDeclaration (Just $ Location 0) In vertexPosition
+  , VariableDeclaration (Just $ Location 1) In vertexColor
+  , VariableDeclaration Nothing Out fragColorOut
+  , MainStart
+  , VariableAssignment GL_POSITION vertexPosition
+  , VariableAssignment fragColorIn vertexColor
+  ]
+
+fragColorIn = Variable "fragColorIn" $ GLSLVec4 GLSLFloat
+fragColorOut = Variable "fragColorOut" $ GLSLVec4 GLSLFloat
+vertexPosition = Variable "vertexPosition" $ GLSLVec4 GLSLFloat
+vertexColor = Variable "vertexColor" $ GLSLVec4 GLSLFloat
diff --git a/src/Types.hs b/src/Types.hs
new file mode 100644
index 0000000..6f338a3
--- /dev/null
+++ b/src/Types.hs
@@ -0,0 +1,122 @@
+{-# LANGUAGE NoImplicitPrelude #-}
+{-# LANGUAGE OverloadedStrings #-}
+
+module Types where
+
+-- IMPORTS --
+
+import Relude
+import qualified Text.Show
+
+-- TYPES --
+
+type Program = Expressions
+
+-- version declaration
+
+type RequestedGLVersion = Int
+data RequestedGLType
+  = Core
+
+instance Show RequestedGLType where
+  show Core = "core"
+
+-- variables
+
+data ParameterQualifier
+  = In
+  | Out
+
+instance Show ParameterQualifier where
+  show In = "in"
+  show Out = "out"
+
+data LayoutQualifier
+  = Location Int
+
+type Variables = [Variable]
+type VariableName = String
+
+data Variable
+  = Variable
+      VariableName
+      GLSLType
+  | GL_POSITION
+
+nameOf :: Variable -> String
+nameOf GL_POSITION = "gl_position"
+nameOf (Variable name _) = name
+
+data GLSLType
+  = GLSLFloat
+  | GLSLVec4 GLSLType
+
+instance Show GLSLType where
+  show (GLSLVec4 _) = "vec4"
+  show GLSLFloat = "float"
+
+-- expressions
+
+type Expressions = [Expression]
+
+data Expression
+  = VersionDeclaration
+      RequestedGLVersion
+      RequestedGLType
+  | VariableDeclaration
+      (Maybe LayoutQualifier)
+      ParameterQualifier
+      Variable
+  | MainStart
+  | VariableAssignment
+      Variable
+      Variable
+
+generateGLSL :: Program -> String
+generateGLSL [] = "}"
+generateGLSL (expression:expressions) =
+  (++)
+    (
+    case expression of
+      VersionDeclaration
+        requestedGLVersion
+        requestedGLType ->
+          "#version " ++
+          (show requestedGLVersion) ++
+          " " ++
+          (show requestedGLType) ++
+          "\n"
+      VariableDeclaration
+        (Just layoutQualifier@(Location location))
+        parameterQualifier
+        (Variable variableName glslType) ->
+          "layout (location = " ++
+          (show location) ++
+          ") " ++
+          (show parameterQualifier) ++
+          " " ++
+          (show glslType) ++
+          " " ++
+          variableName ++
+          ";\n"
+      VariableDeclaration
+        Nothing
+        parameterQualifier
+        (Variable variableName glslType) ->
+          (show parameterQualifier) ++
+          " " ++
+          (show glslType) ++
+          " " ++
+          variableName ++
+          ";\n"
+      MainStart ->
+        "void main()\n{\n"
+      VariableAssignment
+        variable0
+        variable1 ->
+          (nameOf variable0) ++
+          " = " ++
+          (nameOf variable1) ++
+          ";\n"
+    )
+    $ generateGLSL expressions