From 8aaa0569781bf6fcb2189aa4566035fcfb5a850d Mon Sep 17 00:00:00 2001
From: "Niels G. W. Serup" <ngws@metanohi.name>
Date: Mon, 30 Sep 2024 23:30:43 +0200
Subject: [PATCH] Add IsDirectory

---
 byg/src/DependencyGenerator.hs   | 4 ++++
 byg/src/Evaluation/FunctionIO.hs | 5 ++++-
 byg/src/Types/FunctionIO.hs      | 1 +
 3 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/byg/src/DependencyGenerator.hs b/byg/src/DependencyGenerator.hs
index 15cbb1f..92129a9 100644
--- a/byg/src/DependencyGenerator.hs
+++ b/byg/src/DependencyGenerator.hs
@@ -28,6 +28,7 @@ module DependencyGenerator
   , applyTemplate
   , toText
   , listDirectory
+  , isDirectory
   , readTemplate
   , convertImage
   , saveFile
@@ -214,6 +215,9 @@ toText a = runFunction ToText =<< toToken a
 listDirectory :: TokenableTo FilePath a => a -> DepGenM' [FilePath]
 listDirectory a = runFunctionIO ListDirectory =<< toToken a
 
+isDirectory :: TokenableTo FilePath a => a -> DepGenM' Bool
+isDirectory a = runFunctionIO IsDirectory =<< toToken a
+
 readTemplate :: TokenableTo FilePath a => a -> DepGenM' Template
 readTemplate a = runFunctionIO ReadTemplate =<< toToken a
 
diff --git a/byg/src/Evaluation/FunctionIO.hs b/byg/src/Evaluation/FunctionIO.hs
index 1f863e5..877c666 100644
--- a/byg/src/Evaluation/FunctionIO.hs
+++ b/byg/src/Evaluation/FunctionIO.hs
@@ -12,13 +12,16 @@ import qualified Text.Pandoc as P
 import qualified Text.Blaze.Html.Renderer.Text as B
 import qualified Codec.Picture as CP
 import qualified Codec.Picture.STBIR as CPS
-import System.Directory (listDirectory, createDirectory, copyFile)
+import System.Directory (listDirectory, doesDirectoryExist, createDirectory, copyFile)
 
 evalFunctionIO :: FunctionIO -> Value -> IO Value
 evalFunctionIO f x = case (f, x) of
   (ListDirectory, String s) ->
     (List . map toValue) <$> listDirectory s
 
+  (IsDirectory, String s) ->
+    Bool <$> doesDirectoryExist s
+
   (ReadTemplate, String s) -> do
     t <- T.readFile s
     let c = "CONTENT"
diff --git a/byg/src/Types/FunctionIO.hs b/byg/src/Types/FunctionIO.hs
index 24276f9..87e6dbb 100644
--- a/byg/src/Types/FunctionIO.hs
+++ b/byg/src/Types/FunctionIO.hs
@@ -5,6 +5,7 @@ module Types.FunctionIO
 import Language.Haskell.TH.Syntax (Lift)
 
 data FunctionIO = ListDirectory
+                | IsDirectory
                 | ReadTemplate
                 | ConvertImage
                 | SaveFile