From 347cc07c93c3d90bc23f531874835518b42c7fc7 Mon Sep 17 00:00:00 2001
From: "Niels G. W. Serup" <ngws@metanohi.name>
Date: Sun, 6 Oct 2024 16:04:22 +0200
Subject: [PATCH] Begin generalizing elemOf

---
 byg/src/Function.hs      | 15 ++++++++++-----
 byg/src/SiteGenerator.hs |  2 +-
 2 files changed, 11 insertions(+), 6 deletions(-)

diff --git a/byg/src/Function.hs b/byg/src/Function.hs
index bd22d26..14e79db 100644
--- a/byg/src/Function.hs
+++ b/byg/src/Function.hs
@@ -5,6 +5,7 @@ module Function
   , fileComponents
   , lowerString
   , elemOf
+  , elemOfString
   , makeTemplate
   , applyTemplate
   , toText
@@ -15,6 +16,7 @@ module Function
 import Prelude hiding (String, FilePath)
 
 import Types.Values
+import Types.Value (Valuable)
 import Types.Function
 import Types.Token (Token(..))
 import DependencyGenerator (DepGenM, TokenableTo(..), toTupleToken, runFunction)
@@ -75,12 +77,15 @@ lowerString :: TokenableTo String a => a -> DepGenM (Token String)
 lowerString a = runFunction LowerString =<< toToken a
 
 
-data ElemOf = ElemOf deriving (Show, Lift)
-instance IsFunction ElemOf (String, [String]) Bool where
-  evalFunction ElemOf (y, ys) = y `elem` ys
+data ElemOf a = ElemOf a deriving (Show, Lift)
+instance (Show a, Lift a, Valuable a, Eq a) => IsFunction (ElemOf a) (a, [a]) Bool where
+  evalFunction (ElemOf _) (y, ys) = y `elem` ys
 
-elemOf :: (TokenableTo String a, TokenableTo [String] b) => a -> b -> DepGenM (Token Bool)
-elemOf a b = runFunction ElemOf =<< toTupleToken a b
+elemOf :: (Show t, Lift t, Valuable t, Eq t, TokenableTo t a, TokenableTo [t] b) => t -> a -> b -> DepGenM (Token Bool)
+elemOf witness a b = runFunction (ElemOf witness) =<< toTupleToken a b
+
+elemOfString :: (TokenableTo String a, TokenableTo [String] b) => a -> b -> DepGenM (Token Bool)
+elemOfString a b = elemOf "" a b
 
 
 data MakeTemplate = MakeTemplate deriving (Show, Lift)
diff --git a/byg/src/SiteGenerator.hs b/byg/src/SiteGenerator.hs
index 7fda704..6c6f2de 100644
--- a/byg/src/SiteGenerator.hs
+++ b/byg/src/SiteGenerator.hs
@@ -17,7 +17,7 @@ copyTo path targetDir = do
 hasExtension :: (TokenableTo [String] a, TokenableTo FilePath b) => a -> b -> DepGenM (Token Bool)
 hasExtension exts filename = do
   ext <- lowerString =<< untupleSndDepGenM =<< fileComponents filename
-  ext `elemOf` exts
+  ext `elemOfString` exts
 
 handleRecipeDir :: Token FilePath -> Token Template -> Token FilePath -> Token FilePath -> DepGenM ()
 handleRecipeDir outputDir htmlTemplate indexName dir = do