From 6b4d8bb98390d06a04d8afa0643a75c6762b179e Mon Sep 17 00:00:00 2001
From: Nicolas Mattia <nicolas@nmattia.com>
Date: Wed, 30 Jan 2019 19:14:40 +0100
Subject: [PATCH] Force and infer executable names

---
 snack-lib/build.nix        | 14 +++++++++-----
 snack-lib/default.nix      |  5 ++++-
 snack-lib/package-spec.nix | 10 +++++++++-
 3 files changed, 22 insertions(+), 7 deletions(-)

diff --git a/snack-lib/build.nix b/snack-lib/build.nix
index 87d2060..7d46829 100644
--- a/snack-lib/build.nix
+++ b/snack-lib/build.nix
@@ -27,15 +27,19 @@ rec {
   buildLibrary = ghcWith: modSpecs:
     buildModulesRec ghcWith {} modSpecs;
 
-  linkMainModule = ghcWith: mod: # main module
+  linkMainModule =
+      { ghcWith
+      , moduleSpec # The module to build
+      , name # The name to give the executable
+      }:
     let
-      objAttrs = buildMain ghcWith mod;
+      objAttrs = buildMain ghcWith moduleSpec;
       objList = lib.attrsets.mapAttrsToList (x: y: y) objAttrs;
-      deps = allTransitiveDeps [mod];
+      deps = allTransitiveDeps [moduleSpec];
       ghc = ghcWith deps;
-      ghcOptsArgs = lib.strings.escapeShellArgs mod.moduleGhcOpts;
+      ghcOptsArgs = lib.strings.escapeShellArgs moduleSpec.moduleGhcOpts;
       packageList = map (p: "-package ${p}") deps;
-      relExePath = "bin/${lib.strings.toLower mod.moduleName}";
+      relExePath = "bin/${name}";
       drv = runCommand "linker" {}
         ''
           mkdir -p $out/bin
diff --git a/snack-lib/default.nix b/snack-lib/default.nix
index 94f0c1d..d7d53fe 100644
--- a/snack-lib/default.nix
+++ b/snack-lib/default.nix
@@ -41,7 +41,10 @@ let
     buildLibrary ghcWith (libraryModSpecs pkgSpec);
 
   buildAsExecutable = pkgSpec:
-    let drv = linkMainModule ghcWith (executableMainModSpec pkgSpec);
+    let
+      moduleSpec = executableMainModSpec pkgSpec;
+      name = pkgSpec.packageName;
+      drv = linkMainModule { inherit moduleSpec name ghcWith; };
     in
       { out = drv.out;
         exe_path = "${drv.out}/${drv.relExePath}";
diff --git a/snack-lib/package-spec.nix b/snack-lib/package-spec.nix
index 4aa2674..76ea49c 100644
--- a/snack-lib/package-spec.nix
+++ b/snack-lib/package-spec.nix
@@ -18,8 +18,16 @@ rec {
     , extra-directories ? []
     , packages ? []
     }:
+    with
+    rec {
+      isExe = ! builtins.isNull main;
+      pName =
+        if isExe && builtins.isNull name
+        then lib.strings.toLower main
+        else name;
+    };
     { packageIsExe = ! builtins.isNull main;
-      packageName = name;
+      packageName = pName;
       packageMain = main;
       packageSourceDirs =
         if builtins.isList src