Add better support for Haskell stack compiler tools (#1851)

* Add better support for Haskell stack compiler tools

This commit adds support for `stack` as the executable of a tool. This
follows a pattern that has been implemented for `bundler`'s tool chain.

* Move hlint command to linter file
* Add vader test for stack exec handling
* Update ghc-mod to support stack execution

`ghc-mod` was previously broken into 2 linters.

1. ghc_mod
2. stack_ghc_mod

This additional linter is not necessary with proper support for
executable variables and `stack exec` handling.

* Support stack exec in hfmt
* Support stack in hdevtools

6 files changed, 33 insertions, 9 deletions

diff --git a/autoload/ale/fixers/brittany.vim b/autoload/ale/fixers/brittany.vim
index 57c77325..c2448348 100644
--- a/autoload/ale/fixers/brittany.vim
+++ b/autoload/ale/fixers/brittany.vim
@@ -3,11 +3,17 @@
 
 call ale#Set('haskell_brittany_executable', 'brittany')
 
-function! ale#fixers#brittany#Fix(buffer) abort
+function! ale#fixers#brittany#GetExecutable(buffer) abort
     let l:executable = ale#Var(a:buffer, 'haskell_brittany_executable')
 
+    return ale#handlers#haskell_stack#EscapeExecutable(l:executable, 'brittany')
+endfunction
+
+function! ale#fixers#brittany#Fix(buffer) abort
+    let l:executable = ale#fixers#brittany#GetExecutable(a:buffer)
+
     return {
-    \   'command': ale#Escape(l:executable)
+    \   'command': l:executable
     \       . ' --write-mode inplace'
     \       . ' %t',
     \   'read_temporary_file': 1,
diff --git a/autoload/ale/fixers/hfmt.vim b/autoload/ale/fixers/hfmt.vim
index ea061da4..0407b713 100644
--- a/autoload/ale/fixers/hfmt.vim
+++ b/autoload/ale/fixers/hfmt.vim
@@ -7,7 +7,7 @@ function! ale#fixers#hfmt#Fix(buffer) abort
     let l:executable = ale#Var(a:buffer, 'haskell_hfmt_executable')
 
     return {
-    \   'command': ale#Escape(l:executable)
+    \   'command': ale#handlers#haskell_stack#EscapeExecutable(l:executable, 'hfmt')
     \       . ' -w'
     \       . ' %t',
     \   'read_temporary_file': 1,
diff --git a/autoload/ale/fixers/hlint.vim b/autoload/ale/fixers/hlint.vim
index 94dd736e..88779a55 100644
--- a/autoload/ale/fixers/hlint.vim
+++ b/autoload/ale/fixers/hlint.vim
@@ -1,13 +1,10 @@
 " Author: eborden <evan@evan-borden.com>
 " Description: Integration of hlint refactor with ALE.
 "
-call ale#Set('haskell_hlint_executable', 'hlint')
 
 function! ale#fixers#hlint#Fix(buffer) abort
-    let l:executable = ale#Var(a:buffer, 'haskell_hlint_executable')
-
     return {
-    \   'command': ale#Escape(l:executable)
+    \   'command': ale#handlers#hlint#GetExecutable(a:buffer)
     \       . ' --refactor'
     \       . ' --refactor-options="--inplace"'
     \       . ' %t',
diff --git a/autoload/ale/fixers/stylish_haskell.vim b/autoload/ale/fixers/stylish_haskell.vim
index a352312f..ce71c1ce 100644
--- a/autoload/ale/fixers/stylish_haskell.vim
+++ b/autoload/ale/fixers/stylish_haskell.vim
@@ -3,11 +3,17 @@
 "
 call ale#Set('haskell_stylish_haskell_executable', 'stylish-haskell')
 
-function! ale#fixers#stylish_haskell#Fix(buffer) abort
+function! ale#fixers#stylish_haskell#GetExecutable(buffer) abort
     let l:executable = ale#Var(a:buffer, 'haskell_stylish_haskell_executable')
 
+    return ale#handlers#haskell_stack#EscapeExecutable(l:executable, 'stylish-haskell')
+endfunction
+
+function! ale#fixers#stylish_haskell#Fix(buffer) abort
+    let l:executable = ale#fixers#stylish_haskell#GetExecutable(a:buffer)
+
     return {
-    \   'command': ale#Escape(l:executable)
+    \   'command': l:executable
     \       . ' --inplace'
     \       . ' %t',
     \   'read_temporary_file': 1,
diff --git a/autoload/ale/handlers/haskell_stack.vim b/autoload/ale/handlers/haskell_stack.vim
new file mode 100644
index 00000000..108301a9
--- /dev/null
+++ b/autoload/ale/handlers/haskell_stack.vim
@@ -0,0 +1,7 @@
+function! ale#handlers#haskell_stack#EscapeExecutable(executable, stack_exec) abort
+    let l:exec_args = a:executable =~? 'stack$'
+    \   ? ' exec ' . ale#Escape(a:stack_exec) . ' --'
+    \   : ''
+
+    return ale#Escape(a:executable) . l:exec_args
+endfunction
diff --git a/autoload/ale/handlers/hlint.vim b/autoload/ale/handlers/hlint.vim
new file mode 100644
index 00000000..b9a8c322
--- /dev/null
+++ b/autoload/ale/handlers/hlint.vim
@@ -0,0 +1,8 @@
+call ale#Set('haskell_hlint_executable', 'hlint')
+call ale#Set('haskell_hlint_options', get(g:, 'hlint_options', ''))
+
+function! ale#handlers#hlint#GetExecutable(buffer) abort
+    let l:executable = ale#Var(a:buffer, 'haskell_hlint_executable')
+
+    return ale#handlers#haskell_stack#EscapeExecutable(l:executable, 'hlint')
+endfunction