Hi, Currently I'm trying to lern Haskell by doing. After doing some examples I plan to solve an ICFP task (see subject). In short: build an interpreter for a stack based language thata describes a 3D scene. Ray trace this scene in an image. My current source state can be found here: http://code.google.com/p/hgmltracer/source/browse/ My first goal is to develop the interpreter of the GML language. My source contains a data GmlToken with various constructors for the different operators, sequences, int, real, string an so on. Some code for the evaluation is also there und working. But the parser converting a string (contained in the program file provided as command line argument) is hard stuff and I'm stuck. Can any one help me with ideas or concepts for this parser? Thanks