diff --git a/ffi/gles3-export.c b/ffi/gles3-export.c
index 2e32429..79e7a11 100644
--- a/ffi/gles3-export.c
+++ b/ffi/gles3-export.c
@@ -7,7 +7,6 @@
 unsigned int VERTEX_SHADER = GL_VERTEX_SHADER;
 unsigned int FRAGMENT_SHADER = GL_FRAGMENT_SHADER;
 unsigned int TRIANGLES = GL_TRIANGLES;
-unsigned int TRIANGLE_FAN = GL_TRIANGLE_FAN;
 unsigned int STATIC_DRAW = GL_STATIC_DRAW;
 unsigned int DYNAMIC_DRAW = GL_DYNAMIC_DRAW;
 
diff --git a/ffi/gles3-import.sml b/ffi/gles3-import.sml
index d876cea..1afc329 100644
--- a/ffi/gles3-import.sml
+++ b/ffi/gles3-import.sml
@@ -10,16 +10,23 @@ struct
   (* OpenGL constants used. *)
   val (VERTEX_SHADER, _) =
     _symbol "VERTEX_SHADER" public : ( unit -> shader_type ) * ( shader_type -> unit );
+  val VERTEX_SHADER = VERTEX_SHADER ()
+
   val (FRAGMENT_SHADER, _) =
     _symbol "FRAGMENT_SHADER" public : ( unit -> shader_type ) * ( shader_type -> unit );
+  val FRAGMENT_SHADER = FRAGMENT_SHADER ()
+
   val (TRIANGLES, _) =
     _symbol "TRIANGLES" public : ( unit -> draw_mode ) * ( draw_mode -> unit );
-  val (TRIANGLE_FAN, _) =
-    _symbol "TRIANGLE_FAN" public : ( unit -> draw_mode ) * ( draw_mode -> unit );
+  val TRIANGLES = TRIANGLES ()
+
   val (STATIC_DRAW, _) =
     _symbol "STATIC_DRAW" public : ( unit -> update_mode ) * ( update_mode -> unit );
+  val STATIC_DRAW = STATIC_DRAW ()
+
   val (DYNAMIC_DRAW, _) =
     _symbol "DYNAMIC_DRAW" public : ( unit -> update_mode ) * ( update_mode -> unit );
+  val DYNAMIC_DRAW = DYNAMIC_DRAW ()
 
   (* OpenGL functions used. *)
   val loadGlad = _import "loadGlad" public : unit -> unit;
@@ -44,15 +51,13 @@ struct
   val attachShader = _import "attachShader" public : program * shader -> unit;
   val linkProgram = _import "linkProgram" public : program -> unit;
   val useProgram = _import "useProgram" public : program -> unit;
+
+  val deleteShader = _import "deleteShader" public : program -> unit;
   val deleteProgram = _import "deleteProgram" public : program -> unit;
 
   val clearColor =
     _import "clearColor" public : Real32.real * Real32.real * Real32.real * Real32.real -> unit;
   val clear = _import "clear" public : unit -> unit;
-  val drawArrays = _import "drawArrays" public : draw_mode * int * int -> unit;
 
-  val getUniformLocation =
-    _import "getUniformLocation" public : program * string -> int;
-  val uniform4f =
-    _import "uniform4f" public : int * Real32.real * Real32.real * Real32.real * Real32.real -> unit;
+  val drawArrays = _import "drawArrays" public : draw_mode * int * int -> unit;
 end
diff --git a/ffi/glfw-input.sml b/ffi/glfw-input.sml
index f83307d..1759120 100644
--- a/ffi/glfw-input.sml
+++ b/ffi/glfw-input.sml
@@ -5,8 +5,13 @@ struct
   (* Constants. *)
   val (PRESS, _) =
     _symbol "PRESS" public : ( unit -> int ) * ( int -> unit );
+  val PRESS = PRESS ()
+
   val (REPEAT, _) =
     _symbol "REPEAT" public : ( unit -> int ) * ( int -> unit );
+  val REPEAT = REPEAT ()
+
   val (RELEASE, _) =
     _symbol "RELEASE" public : ( unit -> int ) * ( int -> unit );
+  val RELEASE = RELEASE ()
 end
diff --git a/shell/gl-shaders.sml b/shell/gl-shaders.sml
new file mode 100644
index 0000000..f426c2e
--- /dev/null
+++ b/shell/gl-shaders.sml
@@ -0,0 +1,23 @@
+structure GlShaders =
+struct
+  val xyrgbVertexShaderString =
+    "#version 300 es\n\
+    \layout (location = 0) in vec2 apos;\n\
+    \layout (location = 1) in vec3 col;\n\
+    \out vec3 frag_col;\n\
+    \void main()\n\
+    \{\n\
+    \   frag_col = col;\n\
+    \   gl_Position = vec4(apos.x, apos.y, 0.0f, 1.0f);\n\
+    \}"
+
+  val rgbFragmentShaderString =
+    "#version 300 es\n\
+    \precision mediump float;\n\
+    \in vec3 frag_col;\n\
+    \out vec4 FragColor;\n\
+    \void main()\n\
+    \{\n\
+    \   FragColor = vec4(frag_col.x, frag_col.y, frag_col.z, 1.0f);\n\
+    \}"
+end
diff --git a/shf b/shf
index 821dd0f..baa6fde 100755
Binary files a/shf and b/shf differ
diff --git a/shf.mlb b/shf.mlb
index 3f543b1..8f0d450 100644
--- a/shf.mlb
+++ b/shf.mlb
@@ -14,4 +14,5 @@ in
   ffi/glfw-input.sml
 end
 
+shell/gl-shaders.sml
 shell/shell.sml