Unicode normalize slugs

Ref: https://github.com/srid/neuron/issues/611

CHANGELOG.md

@@ -1,9 +1,11 @@
 # Revision history for ema
 
-## Unreleased
+## Unreleased (0.2.0.0)
 
-- Remove Ex03_Documentation.hs (moved to separate repo, `ema-docs`)
-- Add `Ord` instance to `Slug`
+- `Ema.Slug`
+  - Add `Ord` instance to `Slug`
+  - Unicode normalize slugs using NFC
+- Add default implementation based on Enum for `staticRoute`
 - Helpers.FileSystem
   - add `mountOnLVar`
 - Helpers.Tailwind
@@ -11,8 +13,9 @@
   - Add twind shim *before* application's head
 - Helpers.Markdown
   - add helpers to parse markdown; `parseMarkdownWithFrontMatter` and `parseMarkdown`
-- Add Ex03_Basic.hs example
-- Add default implementation based on Enum for `staticRoute`
+- Examples
+  - Remove Ex03_Documentation.hs (moved to separate repo, `ema-docs`)
+  - Add Ex03_Basic.hs example
 
 ## 0.1.0.0 -- 2021-04-26
 

ema.cabal

@@ -56,6 +56,7 @@ library
     , unliftio
     , wai
     , wai-middleware-static
+    , unicode-transforms
     , wai-websockets
     , warp
     , websockets

src/Ema/Route/Slug.hs

@@ -3,6 +3,7 @@
 module Ema.Route.Slug where
 
 import qualified Data.Text as T
+import qualified Data.Text.Normalize as UT
 
 -- | An URL path is made of multiple slugs, separated by '/'
 newtype Slug = Slug {unSlug :: Text}
@@ -13,4 +14,8 @@ instance IsString Slug where
   fromString (toText -> s) =
     if "/" `T.isInfixOf` s
       then error ("Slug cannot contain a slash: " <> s)
-      else Slug s
+      else Slug (unicodeNormalize s)
+    where
+      -- Normalize varying non-ascii strings (in filepaths / slugs) to one
+      -- representation, so that they can be reliably linked to.
+      unicodeNormalize = UT.normalize UT.NFC . toText