Refactor: Broke up eGraphGP, added optional rng seed to RegressionConfig, added nix flake for simple dev setup

.gitignore

@@ -27,3 +27,4 @@ bin/
 coverage-html
 .DS_Store
 flake.lock
+data/

README.md

@@ -10,12 +10,15 @@ symbolic-regression integrates symbolic regression capabilities into a DataFrame
 
 ```haskell
 ghci> import qualified DataFrame as D
-ghci> import DataFrame.Functions ((.=))
+ghci> import qualified DataFrame.Functions as F
 ghci> import Symbolic.Regression
 
 -- Load your data
 ghci> df <- D.readParquet "./data/mtcars.parquet"
 
+-- Define mpg as a column reference
+ghci> let mpg = F.col "mpg"
+
 -- Run symbolic regression to predict 'mpg'
 -- NOTE: ALL COLUMNS MUST BE CONVERTED TO DOUBLE FIRST
 -- e.g df' = D.derive "some_column" (F.toDouble (F.col @Int "some_column")) df
@@ -24,19 +27,20 @@ ghci> df <- D.readParquet "./data/mtcars.parquet"
 ghci> exprs <- fit defaultRegressionConfig mpg df
 
 -- View discovered expressions (Pareto front from simplest to most complex)
-ghci> map D.prettyPrint exprs
--- [ qsec,
--- , 57.33 / wt
--- , 10.75 + (1557.67 / disp)]
+ghci> mapM_ (\(i, e) -> putStrLn $ "Model " ++ show i ++ ": " ++ D.prettyPrint e) (zip [1..] exprs)
+
+-- Create named expressions for different complexity levels  
+ghci> import qualified Data.Text as T
+ghci> let levels = zipWith (F..=) (map (T.pack . ("level_" ++) . show) [1..]) exprs
 
--- Create named expressions that we'll use in a dataframe.
-ghci> levels = zipWith (.=) ["level_1", "level_2", "level_3"] exprs
+-- Show the various predictions in our dataframe
+ghci> let df' = D.deriveMany levels df
 
--- Show the various predictions in our dataframe.
-ghci> D.deriveMany levels df
+-- Or pick the best one for prediction
+ghci> let df'' = D.derive "prediction" (last exprs) df'
 
--- Or pick the best one
-ghci> D.derive "prediction" (last exprs) df
+-- Display the results
+ghci> D.display (D.DisplayOptions 5) df''
 ```
 
 ## Configuration
@@ -102,3 +106,14 @@ To install symbolic-regression you'll need:
 * libz: `sudo apt install libz-dev`
 * libnlopt: `sudo apt install libnlopt-dev`
 * libgmp: `sudo apt install libgmp-dev`
+
+### Nix Development Environment
+For Nix users with flakes enabled:
+
+```bash
+git clone <repo-url>
+cd symbolic-regression
+nix develop -c cabal repl
+```
+
+Then follow the Quick Start example above.

flake.nix

@@ -0,0 +1,84 @@
+{
+  description = "DataFrame symbolic regression";
+
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-unstable";
+    flake-parts.url = "github:hercules-ci/flake-parts";
+  };
+
+  outputs =
+    inputs@{ flake-parts, ... }:
+    flake-parts.lib.mkFlake { inherit inputs; } {
+      systems = [
+        "x86_64-linux"
+        "aarch64-linux"
+        "aarch64-darwin"
+        "x86_64-darwin"
+      ];
+
+      perSystem =
+        {
+          config,
+          pkgs,
+          system,
+          ...
+        }:
+        let
+          pkgs' = import inputs.nixpkgs {
+            inherit system;
+            config.allowBroken = true;
+          };
+
+          haskellPackages = pkgs'.haskellPackages.extend (
+            final: prev: {
+              # Use the correct hash that Nix gave us
+              random = pkgs'.haskell.lib.dontCheck (
+                prev.callHackageDirect {
+                  pkg = "random";
+                  ver = "1.3.0";
+                  sha256 = "sha256-AzXPz8oe+9lAS60nRNFiRTEDrFDB0FPLtbvJ9PB7brM=";
+                } { }
+              );
+
+              srtree = pkgs'.haskell.lib.dontCheck (
+                prev.callHackageDirect {
+                  pkg = "srtree";
+                  ver = "2.0.1.6";
+                  sha256 = "sha256-D561wnKoFRr/HSviacsbtF5VnJHehG73LOmWM4TxlNs=";
+                } { }
+              );
+
+              dataframe = pkgs'.haskell.lib.dontCheck (
+                prev.callHackageDirect {
+                  pkg = "dataframe";
+                  ver = "0.4.1.0";
+                  sha256 = "sha256-u4FrhD+oOnQiGazq/TWuL0PzUvLKKAkz679tZSkiMaY=";
+                } { }
+              );
+
+              # Jailbreak packages that depend on old random
+              time-compat = pkgs'.haskell.lib.doJailbreak prev.time-compat;
+              splitmix = pkgs'.haskell.lib.doJailbreak prev.splitmix;
+            }
+          );
+
+        in
+        {
+          packages = {
+            default = config.packages.symbolic-regression;
+            symbolic-regression = haskellPackages.callCabal2nix "symbolic-regression" ./. { };
+          };
+
+          devShells.default = haskellPackages.shellFor {
+            packages = p: [ config.packages.symbolic-regression ];
+            buildInputs = with pkgs'; [
+              cabal-install
+              haskell-language-server
+              git
+              fourmolu
+              nixfmt
+            ];
+          };
+        };
+    };
+}