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+layout: default.liquid
+
+title: 2025-12-18 GLSL EDSL in Haskell part 1
+description: first part of GLSL EDSL development series. We initialize the project and do some planning.
+is_draft: true
+---
+
+all code for this project is available [here](https://git.mtgmonkey.net/Andromeda/hs-glsl). Please contact me if you want an account for contribution or to file issues.
+
+#### goals of this project
+
+I want to generate [GLSL]() from the type-safe environment of Haskell with an [EDSL](). Specifically, I want to functionally declare the glsl shader code I use in my [game](https://git.mtgmonkey.net/Andromeda/hs-game).
+
+At the moment, that's quite a lot. Let's start with a practically bare Haskell/OpenGL project. Let's build our development environment.
+
+``` bash
+mkdir hs-glsl
+cd hs-glsl
+
+# get initial dependencies
+nix-shell -p cabal-install ghc
+cabal init
+# all defaults are ok for our needs EXCEPT the following:
+# Application directory: I chose 4 then put `src`
+# Version: I chose 0.1.0, breaking with PVP in
+#   favor of Semantic Versioning
+# Category: Graphics
+# I also entered my contact, username, and homepage
+```
+
+Great, now we have a `hs-glsl.cabal`, the file that defines our project. Cabal also created a number of other files and directories, namely `src/Main.hs` and `LICENSE`. Running the command `cabal run` will run the project, but it isn't reproducable; how can we do it with Nix? We can create a nix flake as follows:
+
+``` nix
+# flake.nix
+{
+  inputs = {
+    nixpkgs.url = "nixpkgs/nixpkgs-unstable";
+  };
+  outputs = {
+    nixpkgs, self, ...
+  }: let
+    system = "x86_64-linux";
+    pkgs = nixpkgs.legacyPackages.${system};
+  in {
+    packages.${system} = {
+      default =
+        pkgs.haskellPackages.callCabal2nix "hs-glsl" {};
+    };
+    devShells.${system} = {
+      default = pkgs.mkShell {
+        packages = [
+          pkgs.cabal-install
+        ];
+        inputsFrom = [
+          self.packages.${system}.default
+        ];
+      };
+    };
+  };
+}
+```
+
+now `nix develop` puts us in a shell with all of out dependencies, and `nix run` should run the program. Let's use [GLFW-b]() to create a window:
+
+``` yaml
+# hs-glsl.cabal
+...
+executable hs-glsl
+    ...
+    build-depends:
+          base ^>=4.20.2.0
+        , GLFW-b <1000
+...
+```
+
+---
+
+``` hs
+-- | src/Main.hs
+module Main (main) where
+
+-- | windowing library
+import qualified Graphics.UI.GLFW as GLFW
+
+-- | main
+main :: IO ()
+main = do
+  -- initialize GLFW
+  _ <- GLFW.init
+  GLFW.defaultWindowHints
+
+  -- we use GLSL version 3.3 Core here
+  GLFW.windowHint $ GLFW.WindowHint'ContextVersionMajor 3
+  GLFW.windowHint $ GLFW.WindowHint'ContextVersionMinor 3
+  GLFW.windowHint $ GLFW.WindowHint'OpenGLProfile GLFW.OpenGLProfile'Core
+
+  -- monitor required to fullscreen at start
+  monitor <- GLFW.getPrimaryMonitor
+
+  -- actually create the window
+  Just window <- GLFW.createWindow 256 256 "hs-glsl" monitor Nothing
+  GLFW.makeContextCurrent $ Just window
+
+  -- enter loop
+  loop window
+
+-- | loop that runs every frame
+loop :: GLFW.Window -> IO ()
+loop window = do
+  -- swap to next framebuffer
+  GLFW.swapBuffers window
+
+  -- call next frame
+  loop window
+```
+
+Great, a fullscreen window that never closes! I'll go ahead and add a quick key callback so that pressing `esc` closes the program.
+
+```
+-- | src/Main.hs