Hello, I've been experimenting with HOpenGL a little, and have run into strange behaviour when compiling with -O. In particular, while things work as expected when compiling normally, if I compile the following module with -O, drawLine' appears to scale the line by 2, while drawLine works as before. module Lines where import GL drawLine = do pushMatrix beginEnd Lines . sequence_ . map vertex $ [ Vertex2 0 0, Vertex2 0 (1::GLfloat) ] popMatrix drawLine' = do pushMatrix scale 1 1 (1::GLfloat) beginEnd Lines . sequence_ . map vertex $ [ Vertex2 0 0, Vertex2 0 (1::GLfloat) ] popMatrix This was tested using the attached program. I'm using HOpenGL-1.01 with the recent patch, and a ghc from CVS which is about a week old. When compiling Lines.hs with -O, I get /tmp/ghc14725.hc: In function `s8Wy_ret': /tmp/ghc14725.hc:474: warning: implicit declaration of function `glScalef' Also, if I actually compile the test program with -O, it doesn't display anything.