From 59a5db0684922f1318e9c36970290f17a6d7f7ed Mon Sep 17 00:00:00 2001
From: tv <tv@krebsco.de>
Date: Tue, 4 Jun 2024 14:06:57 +0200
Subject: modernize build system

---
 .gitignore |  5 +----
 Makefile   | 21 ---------------------
 README     |  2 ++
 env.nix    | 51 ---------------------------------------------------
 shell.nix  | 31 +++++++++++++++++++++++++++++++
 5 files changed, 34 insertions(+), 76 deletions(-)
 delete mode 100644 Makefile
 create mode 100644 README
 delete mode 100644 env.nix
 create mode 100644 shell.nix

diff --git a/.gitignore b/.gitignore
index 36eacc8..3c203cb 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,4 +1 @@
-*.hi
-*.o
-/.graveyard
-/shell.nix
+/package.nix
diff --git a/Makefile b/Makefile
deleted file mode 100644
index d7ece7f..0000000
--- a/Makefile
+++ /dev/null
@@ -1,21 +0,0 @@
-.PHONY: _default
-_default: ghci
-
-.PHONY: clean
-clean:
-	@find * -type f \( -name \*.o -o -name \*.hi \) -exec rm -v \{\} \;
-
-.PHONY: ghci
-ghci: shell.nix
-	nix-shell --argstr compiler ghc801 --command 'exec ghci -Wall -fobject-code -isrc'
-
-.PHONY: install
-install:
-	$(error to install run "make result && nix-env -i ./result")
-
-.PHONY: result
-result: shell.nix
-	nix-build ./shell.nix
-
-shell.nix: $(wildcard *.cabal)
-	cabal2nix --shell . > $@
diff --git a/README b/README
new file mode 100644
index 0000000..74aa051
--- /dev/null
+++ b/README
@@ -0,0 +1,2 @@
+cabal2nix . > package.nix && nix-shell
+cabal run
diff --git a/env.nix b/env.nix
deleted file mode 100644
index 47a9759..0000000
--- a/env.nix
+++ /dev/null
@@ -1,51 +0,0 @@
-{ nixpkgs ? import <nixpkgs> {} }:
-
-let
-  pname = "hack";
-  version = "2";
-
-  buildInputs = with pkgs; [
-    hsEnv
-  ];
-
-  extraCmds = with pkgs; ''
-    export MANPATH=$(ls -d $(echo "$PATH" | tr : \\n | sed -n 's:\(^/nix/store/[^/]\+\).*:\1/share/man:p') 2>/dev/null | tr \\n :)
-    $(grep export ${hsEnv.outPath}/bin/ghc)
-    ${mkExports staticPkgs}
-  '';
-
-  hsEnv = hsPkgs.ghcWithPackages (self: with self;
-    [
-      cabal-install
-      data-default
-      lens
-      mtl
-      zippers
-
-      #threadscope
-    ]
-  );
-
-  hsPkgs = pkgs.haskellngPackages;
-
-  pkgs = nixpkgs // staticPkgs;
-  staticPkgs = with nixpkgs; {
-  };
-
-  #{{{ mkExports : set -> string
-  # Create shell script that exports a set's attributes.
-  mkExports = set: with builtins; with pkgs.lib.strings;
-    let
-      # XXX attribute names are not escaped, they have to be sane
-      # XXX the value should not contain <newline>
-      mkExport = k: "export ${k}=${escapeSh (getAttr k set)}";
-      escapeSh = stringAsChars (c: "\\${c}");
-    in
-      concatStringsSep "\n" (map mkExport (attrNames set));
-  #}}}
-
-in pkgs.myEnvFun {
-  name = "${pname}-${version}";
-  inherit buildInputs extraCmds;
-}
-# vim: set fdm=marker :
diff --git a/shell.nix b/shell.nix
new file mode 100644
index 0000000..48d4bf4
--- /dev/null
+++ b/shell.nix
@@ -0,0 +1,31 @@
+{ compiler ? "default"
+, nixpkgs ? import <nixpkgs> {}
+}: let
+
+  inherit (nixpkgs) lib pkgs;
+
+  haskellPackages =
+    if compiler == "default" then
+      pkgs.haskellPackages
+    else
+      pkgs.haskell.packages.${compiler};
+
+  drv = haskellPackages.callPackage (import ./package.nix) {};
+
+in
+
+  lib.overrideDerivation drv.env (oldAttrs: {
+    buildInputs = [
+      pkgs.cabal-install
+    ];
+    shellHook = ''
+      CABAL_BUILD_DIR=$HOME/tmp/cache/${drv.pname}
+      cabal() {
+        command=$1; shift
+        ${pkgs.cabal-install}/bin/cabal \
+            "$command" \
+            --builddir="$CABAL_BUILD_DIR" \
+            "$@"
+      }
+    '';
+  })
-- 
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