From 52c63983d85ee49eece41919dad201f9c533c74c Mon Sep 17 00:00:00 2001
From: Futar <Futarimiti@163.com>
Date: Mon, 5 Aug 2024 09:06:42 +0800
Subject: [PATCH 1/3] support multiway-lambda expressions

---
 indent/haskell.vim               | 8 ++++++++
 test/case/cases.in.hs            | 6 ++++++
 test/case/cases.out.hs           | 6 ++++++
 test/case/cases_same_line.in.hs  | 5 +++++
 test/case/cases_same_line.out.hs | 5 +++++
 5 files changed, 30 insertions(+)
 create mode 100644 test/case/cases.in.hs
 create mode 100644 test/case/cases.out.hs
 create mode 100644 test/case/cases_same_line.in.hs
 create mode 100644 test/case/cases_same_line.out.hs

diff --git a/indent/haskell.vim b/indent/haskell.vim
index 54f244a..8696ffd 100644
--- a/indent/haskell.vim
+++ b/indent/haskell.vim
@@ -178,6 +178,14 @@ function! GetHaskellIndent() abort
     return match(line, '\v^\s*%(<where>|.*<let>)?\s*\zs') + &shiftwidth
   endif
 
+  if line =~# '\v\\\s*<cases>\s*%(--.*)?$'
+    return match(line, '\v^\s*%(<where>|.*<let>)?\s*\zs') + &shiftwidth
+  endif
+
+  if line =~# '\v\\\s*<cases>\s*[[:alnum:](-\"'']' 
+    return match(line, '\v\\\s*<cases>\s*\zs\S')
+  endif
+
   if nonblankline =~# '\v^.*[^|]\|[^|].*\='
     return s:after_guard()
   endif
diff --git a/test/case/cases.in.hs b/test/case/cases.in.hs
new file mode 100644
index 0000000..789e112
--- /dev/null
+++ b/test/case/cases.in.hs
@@ -0,0 +1,6 @@
+printGender :: Language -> Gender -> Text
+printGender = \cases
+English Male   -> "Male"
+English Female -> "Female"
+Chinese Male   -> "男性"
+Chinese Female -> "女性"
diff --git a/test/case/cases.out.hs b/test/case/cases.out.hs
new file mode 100644
index 0000000..ab356f5
--- /dev/null
+++ b/test/case/cases.out.hs
@@ -0,0 +1,6 @@
+printGender :: Language -> Gender -> Text
+printGender = \cases
+  English Male   -> "Male"
+  English Female -> "Female"
+  Chinese Male   -> "男性"
+  Chinese Female -> "女性"
diff --git a/test/case/cases_same_line.in.hs b/test/case/cases_same_line.in.hs
new file mode 100644
index 0000000..b068e11
--- /dev/null
+++ b/test/case/cases_same_line.in.hs
@@ -0,0 +1,5 @@
+printGender :: Language -> Gender -> Text
+printGender = \cases English Male   -> "Male"
+English Female -> "Female"
+Chinese Male   -> "男性"
+Chinese Female -> "女性"
diff --git a/test/case/cases_same_line.out.hs b/test/case/cases_same_line.out.hs
new file mode 100644
index 0000000..ec54c47
--- /dev/null
+++ b/test/case/cases_same_line.out.hs
@@ -0,0 +1,5 @@
+printGender :: Language -> Gender -> Text
+printGender = \cases English Male   -> "Male"
+                     English Female -> "Female"
+                     Chinese Male   -> "男性"
+                     Chinese Female -> "女性"

From 2ffd185bdfa83fa47a3489efbcb9194f62dea785 Mon Sep 17 00:00:00 2001
From: Futar <Futarimiti@163.com>
Date: Mon, 5 Aug 2024 09:28:19 +0800
Subject: [PATCH 2/3] include underscore in pattern

---
 indent/haskell.vim | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/indent/haskell.vim b/indent/haskell.vim
index 8696ffd..f02b425 100644
--- a/indent/haskell.vim
+++ b/indent/haskell.vim
@@ -182,7 +182,7 @@ function! GetHaskellIndent() abort
     return match(line, '\v^\s*%(<where>|.*<let>)?\s*\zs') + &shiftwidth
   endif
 
-  if line =~# '\v\\\s*<cases>\s*[[:alnum:](-\"'']' 
+  if line =~# '\v\\\s*<cases>\s*[[:alnum:](_\-\"'']' 
     return match(line, '\v\\\s*<cases>\s*\zs\S')
   endif
 

From 39747d562a64cf6822049e8bf15a72a5a4611fba Mon Sep 17 00:00:00 2001
From: Futar <Futarimiti@163.com>
Date: Mon, 5 Aug 2024 12:14:15 +0800
Subject: [PATCH 3/3] trigger indentation for guards in multiway-lambda
 expressions

---
 indent/haskell.vim          | 2 ++
 test/case/casesguard.in.hs  | 3 +++
 test/case/casesguard.out.hs | 3 +++
 3 files changed, 8 insertions(+)
 create mode 100644 test/case/casesguard.in.hs
 create mode 100644 test/case/casesguard.out.hs

diff --git a/indent/haskell.vim b/indent/haskell.vim
index f02b425..0f514f5 100644
--- a/indent/haskell.vim
+++ b/indent/haskell.vim
@@ -475,6 +475,8 @@ function! s:indent_bar() abort
     let line = getline(i)
     if line =~# '\v^[^[\]]*%([^[\]]*|\[[^[\]]*\])*\[%([^[\]]*|\[[^[\]]*\])*%(--.*)?$'
       return match(line, '\v^[^[\]]*%([^[\]]*|\[[^[\]]*\])*\zs\[([^[\]]*|\[[^[\]]*\])*%(--.*)?$') + &shiftwidth
+    elseif line =~# '\v\\\s*<cases>.*\|'
+      return match(line, '\v\\\s*<cases>.*\zs\|')
     elseif line =~# '\v^\s*%(<where>)?.*[^|]\|[^|].*\='
       return match(line, '\v^\s*%(<where>)?.*[^|]\zs\|[^|].*\=')
     elseif line =~# '\v<data>.*\='
diff --git a/test/case/casesguard.in.hs b/test/case/casesguard.in.hs
new file mode 100644
index 0000000..a919118
--- /dev/null
+++ b/test/case/casesguard.in.hs
@@ -0,0 +1,3 @@
+filter = \cases _ []                 -> []
+p (x:xs) | p x       -> x : filter p xs
+| otherwise ->     filter p xs
diff --git a/test/case/casesguard.out.hs b/test/case/casesguard.out.hs
new file mode 100644
index 0000000..07148b6
--- /dev/null
+++ b/test/case/casesguard.out.hs
@@ -0,0 +1,3 @@
+filter = \cases _ []                 -> []
+                p (x:xs) | p x       -> x : filter p xs
+                         | otherwise ->     filter p xs