Ban use of ==# or ==? in the codebase, and prefer is# or is? instead

61 files changed, 158 insertions, 154 deletions

diff --git a/ale_linters/ansible/ansible_lint.vim b/ale_linters/ansible/ansible_lint.vim
index 192e65b9..7d68cde3 100644
--- a/ale_linters/ansible/ansible_lint.vim
+++ b/ale_linters/ansible/ansible_lint.vim
@@ -21,8 +21,8 @@ function! ale_linters#ansible#ansible_lint#Handle(buffer, lines) abort
     for l:match in ale#util#GetMatches(a:lines, l:pattern)
         let l:code = l:match[4]
 
-        if (l:code ==# 'EANSIBLE002')
-        \ && !ale#Var(a:buffer, 'warn_about_trailing_whitespace')
+        if l:code is# 'EANSIBLE002'
+        \&& !ale#Var(a:buffer, 'warn_about_trailing_whitespace')
             " Skip warnings for trailing whitespace if the option is off.
             continue
         endif
@@ -32,7 +32,7 @@ function! ale_linters#ansible#ansible_lint#Handle(buffer, lines) abort
             \   'lnum': l:match[2] + 0,
             \   'col': l:match[3] + 0,
             \   'text': l:code . ': ' . l:match[5],
-            \   'type': l:code[:0] ==# 'E' ? 'E' : 'W',
+            \   'type': l:code[:0] is# 'E' ? 'E' : 'W',
             \})
         endif
     endfor
diff --git a/ale_linters/coffee/coffeelint.vim b/ale_linters/coffee/coffeelint.vim
index 9db3399c..6d3df353 100644
--- a/ale_linters/coffee/coffeelint.vim
+++ b/ale_linters/coffee/coffeelint.vim
@@ -27,7 +27,7 @@ function! ale_linters#coffee#coffeelint#Handle(buffer, lines) abort
     for l:match in ale#util#GetMatches(a:lines, l:pattern)
         call add(l:output, {
         \   'lnum': str2nr(l:match[1]),
-        \   'type': l:match[3] ==# 'error' ? 'E' : 'W',
+        \   'type': l:match[3] is# 'error' ? 'E' : 'W',
         \   'text': l:match[4],
         \})
     endfor
diff --git a/ale_linters/d/dmd.vim b/ale_linters/d/dmd.vim
index bd3f9d55..b91238ae 100644
--- a/ale_linters/d/dmd.vim
+++ b/ale_linters/d/dmd.vim
@@ -60,7 +60,7 @@ function! ale_linters#d#dmd#Handle(buffer, lines) abort
         call add(l:output, {
         \   'lnum': l:match[1],
         \   'col': l:match[2],
-        \   'type': l:match[3] ==# 'Warning' ? 'W' : 'E',
+        \   'type': l:match[3] is# 'Warning' ? 'W' : 'E',
         \   'text': l:match[4],
         \})
     endfor
diff --git a/ale_linters/dart/dartanalyzer.vim b/ale_linters/dart/dartanalyzer.vim
index 8f440571..f7b82c4b 100644
--- a/ale_linters/dart/dartanalyzer.vim
+++ b/ale_linters/dart/dartanalyzer.vim
@@ -22,7 +22,7 @@ function! ale_linters#dart#dartanalyzer#Handle(buffer, lines) abort
 
     for l:match in ale#util#GetMatches(a:lines, l:pattern)
         call add(l:output, {
-        \   'type': l:match[1] ==# 'error' ? 'E' : 'W',
+        \   'type': l:match[1] is# 'error' ? 'E' : 'W',
         \   'text': l:match[6] . ': ' . l:match[2],
         \   'lnum': str2nr(l:match[4]),
         \   'col': str2nr(l:match[5]),
diff --git a/ale_linters/dockerfile/hadolint.vim b/ale_linters/dockerfile/hadolint.vim
index 4063bf1b..563be630 100644
--- a/ale_linters/dockerfile/hadolint.vim
+++ b/ale_linters/dockerfile/hadolint.vim
@@ -45,9 +45,9 @@ function! ale_linters#dockerfile#hadolint#GetExecutable(buffer) abort
     let l:use_docker = ale#Var(a:buffer, 'dockerfile_hadolint_use_docker')
 
     " check for mandatory directives
-    if l:use_docker ==# 'never'
+    if l:use_docker is# 'never'
         return 'hadolint'
-    elseif l:use_docker ==# 'always'
+    elseif l:use_docker is# 'always'
         return 'docker'
     endif
 
@@ -62,7 +62,7 @@ endfunction
 
 function! ale_linters#dockerfile#hadolint#GetCommand(buffer) abort
     let l:command = ale_linters#dockerfile#hadolint#GetExecutable(a:buffer)
-    if l:command ==# 'docker'
+    if l:command is# 'docker'
         return 'docker run --rm -i ' . ale#Var(a:buffer, 'dockerfile_hadolint_docker_image')
     endif
     return 'hadolint -'
diff --git a/ale_linters/elixir/credo.vim b/ale_linters/elixir/credo.vim
index 46f75457..3699dd23 100644
--- a/ale_linters/elixir/credo.vim
+++ b/ale_linters/elixir/credo.vim
@@ -11,9 +11,9 @@ function! ale_linters#elixir#credo#Handle(buffer, lines) abort
         let l:type = l:match[3]
         let l:text = l:match[4]
 
-        if l:type ==# 'C'
+        if l:type is# 'C'
             let l:type = 'E'
-        elseif l:type ==# 'R'
+        elseif l:type is# 'R'
             let l:type = 'W'
         endif
 
diff --git a/ale_linters/elixir/dogma.vim b/ale_linters/elixir/dogma.vim
index e3b24711..b4f32b04 100644
--- a/ale_linters/elixir/dogma.vim
+++ b/ale_linters/elixir/dogma.vim
@@ -11,9 +11,9 @@ function! ale_linters#elixir#dogma#Handle(buffer, lines) abort
         let l:type = l:match[3]
         let l:text = l:match[4]
 
-        if l:type ==# 'C'
+        if l:type is# 'C'
             let l:type = 'E'
-        elseif l:type ==# 'R'
+        elseif l:type is# 'R'
             let l:type = 'W'
         endif
 
diff --git a/ale_linters/elm/make.vim b/ale_linters/elm/make.vim
index 0a570ff6..5f7705b8 100644
--- a/ale_linters/elm/make.vim
+++ b/ale_linters/elm/make.vim
@@ -7,16 +7,16 @@ function! ale_linters#elm#make#Handle(buffer, lines) abort
     let l:temp_dir = l:is_windows ? $TMP : $TMPDIR
     let l:unparsed_lines = []
     for l:line in a:lines
-        if l:line[0] ==# '['
+        if l:line[0] is# '['
             let l:errors = json_decode(l:line)
 
             for l:error in l:errors
                 " Check if file is from the temp directory.
                 " Filters out any errors not related to the buffer.
                 if l:is_windows
-                    let l:file_is_buffer = l:error.file[0:len(l:temp_dir) - 1] ==? l:temp_dir
+                    let l:file_is_buffer = l:error.file[0:len(l:temp_dir) - 1] is? l:temp_dir
                 else
-                    let l:file_is_buffer = l:error.file[0:len(l:temp_dir) - 1] ==# l:temp_dir
+                    let l:file_is_buffer = l:error.file[0:len(l:temp_dir) - 1] is# l:temp_dir
                 endif
 
                 if l:file_is_buffer
@@ -25,7 +25,7 @@ function! ale_linters#elm#make#Handle(buffer, lines) abort
                     \    'col': l:error.region.start.column,
                     \    'end_lnum': l:error.region.end.line,
                     \    'end_col': l:error.region.end.column,
-                    \    'type': (l:error.type ==? 'error') ? 'E' : 'W',
+                    \    'type': (l:error.type is? 'error') ? 'E' : 'W',
                     \    'text': l:error.overview,
                     \    'detail': l:error.overview . "\n\n" . l:error.details
                     \})
diff --git a/ale_linters/erlang/erlc.vim b/ale_linters/erlang/erlc.vim
index 162c7ec3..559dc679 100644
--- a/ale_linters/erlang/erlc.vim
+++ b/ale_linters/erlang/erlc.vim
@@ -27,7 +27,7 @@ function! ale_linters#erlang#erlc#Handle(buffer, lines) abort
     let l:pattern_no_module_definition = '\v(no module definition)$'
     let l:pattern_unused = '\v(.* is unused)$'
 
-    let l:is_hrl = fnamemodify(bufname(a:buffer), ':e') ==# 'hrl'
+    let l:is_hrl = fnamemodify(bufname(a:buffer), ':e') is# 'hrl'
 
     for l:line in a:lines
         let l:match = matchlist(l:line, l:pattern)
diff --git a/ale_linters/fortran/gcc.vim b/ale_linters/fortran/gcc.vim
index a59c6564..5f2ac018 100644
--- a/ale_linters/fortran/gcc.vim
+++ b/ale_linters/fortran/gcc.vim
@@ -44,7 +44,7 @@ function! ale_linters#fortran#gcc#Handle(buffer, lines) abort
 
             " Now we have the text, we can set it and add the error.
             let l:last_loclist_obj.text = l:match[2]
-            let l:last_loclist_obj.type = l:match[1] ==# 'Warning' ? 'W' : 'E'
+            let l:last_loclist_obj.type = l:match[1] is# 'Warning' ? 'W' : 'E'
             call add(l:output, l:last_loclist_obj)
         else
             let l:last_loclist_obj = {
diff --git a/ale_linters/go/gometalinter.vim b/ale_linters/go/gometalinter.vim
index 6d10871d..f1abfc83 100644
--- a/ale_linters/go/gometalinter.vim
+++ b/ale_linters/go/gometalinter.vim
@@ -32,7 +32,7 @@ function! ale_linters#go#gometalinter#Handler(buffer, lines) abort
         call add(l:output, {
         \   'lnum': l:match[2] + 0,
         \   'col': l:match[3] + 0,
-        \   'type': tolower(l:match[4]) ==# 'warning' ? 'W' : 'E',
+        \   'type': tolower(l:match[4]) is# 'warning' ? 'W' : 'E',
         \   'text': l:match[5],
         \})
     endfor
diff --git a/ale_linters/haskell/hlint.vim b/ale_linters/haskell/hlint.vim
index 91e65123..be40d92c 100644
--- a/ale_linters/haskell/hlint.vim
+++ b/ale_linters/haskell/hlint.vim
@@ -5,9 +5,9 @@ function! ale_linters#haskell#hlint#Handle(buffer, lines) abort
     let l:output = []
 
     for l:error in ale#util#FuzzyJSONDecode(a:lines, [])
-        if l:error.severity ==# 'Error'
+        if l:error.severity is# 'Error'
             let l:type = 'E'
-        elseif l:error.severity ==# 'Suggestion'
+        elseif l:error.severity is# 'Suggestion'
             let l:type = 'I'
         else
             let l:type = 'W'
diff --git a/ale_linters/html/tidy.vim b/ale_linters/html/tidy.vim
index c9fdbc7c..4a55d62f 100644
--- a/ale_linters/html/tidy.vim
+++ b/ale_linters/html/tidy.vim
@@ -46,7 +46,7 @@ function! ale_linters#html#tidy#Handle(buffer, lines) abort
     for l:match in ale#util#GetMatches(a:lines, l:pattern)
         let l:line = l:match[1] + 0
         let l:col = l:match[2] + 0
-        let l:type = l:match[3] ==# 'Error' ? 'E' : 'W'
+        let l:type = l:match[3] is# 'Error' ? 'E' : 'W'
         let l:text = l:match[4]
 
         call add(l:output, {
diff --git a/ale_linters/java/javac.vim b/ale_linters/java/javac.vim
index 97530882..d4566abf 100644
--- a/ale_linters/java/javac.vim
+++ b/ale_linters/java/javac.vim
@@ -68,14 +68,14 @@ function! ale_linters#java#javac#Handle(buffer, lines) abort
                 let l:output[-1].col = len(l:match[1])
         elseif empty(l:match[3])
             " Add symbols to 'cannot find symbol' errors.
-            if l:output[-1].text ==# 'error: cannot find symbol'
+            if l:output[-1].text is# 'error: cannot find symbol'
                 let l:output[-1].text .= ': ' . l:match[2]
             endif
         else
             call add(l:output, {
             \   'lnum': l:match[1] + 0,
             \   'text': l:match[2] . ':' . l:match[3],
-            \   'type': l:match[2] ==# 'error' ? 'E' : 'W',
+            \   'type': l:match[2] is# 'error' ? 'E' : 'W',
             \})
         endif
     endfor
diff --git a/ale_linters/javascript/flow.vim b/ale_linters/javascript/flow.vim
index f3e5deff..0dd64535 100644
--- a/ale_linters/javascript/flow.vim
+++ b/ale_linters/javascript/flow.vim
@@ -46,7 +46,7 @@ function! s:GetJSONLines(lines) abort
     let l:start_index = 0
 
     for l:line in a:lines
-        if l:line[:0] ==# '{'
+        if l:line[:0] is# '{'
             break
         endif
 
@@ -77,13 +77,13 @@ function! ale_linters#javascript#flow#Handle(buffer, lines) abort
             " In certain cases, `l:message.loc.source` points to a different path
             " than the buffer one, thus we skip this loc information too.
             if has_key(l:message, 'loc')
-            \&& l:line ==# 0
+            \&& l:line is# 0
             \&& ale#path#IsBufferPath(a:buffer, l:message.loc.source)
                 let l:line = l:message.loc.start.line + 0
                 let l:col = l:message.loc.start.column + 0
             endif
 
-            if l:text ==# ''
+            if l:text is# ''
                 let l:text = l:message.descr . ':'
             else
                 let l:text = l:text . ' ' . l:message.descr
@@ -98,7 +98,7 @@ function! ale_linters#javascript#flow#Handle(buffer, lines) abort
         \   'lnum': l:line,
         \   'col': l:col,
         \   'text': l:text,
-        \   'type': l:error.level ==# 'error' ? 'E' : 'W',
+        \   'type': l:error.level is# 'error' ? 'E' : 'W',
         \})
     endfor
 
diff --git a/ale_linters/kotlin/kotlinc.vim b/ale_linters/kotlin/kotlinc.vim
index ebaf4456..c8d238b2 100644
--- a/ale_linters/kotlin/kotlinc.vim
+++ b/ale_linters/kotlin/kotlinc.vim
@@ -124,7 +124,7 @@ function! ale_linters#kotlin#kotlinc#Handle(buffer, lines) abort
         if l:buf_abspath !=# l:curbuf_abspath
             continue
         endif
-        let l:type_marker_str = l:type ==# 'warning' ? 'W' : 'E'
+        let l:type_marker_str = l:type is# 'warning' ? 'W' : 'E'
 
         call add(l:output, {
         \   'lnum': l:line,
@@ -145,7 +145,7 @@ function! ale_linters#kotlin#kotlinc#Handle(buffer, lines) abort
         let l:type = l:match[1]
         let l:text = l:match[2]
 
-        let l:type_marker_str = l:type ==# 'warning' || l:type ==# 'info' ? 'W' : 'E'
+        let l:type_marker_str = l:type is# 'warning' || l:type is# 'info' ? 'W' : 'E'
 
         call add(l:output, {
         \   'lnum': 1,
diff --git a/ale_linters/matlab/mlint.vim b/ale_linters/matlab/mlint.vim
index 851e398a..32766334 100644
--- a/ale_linters/matlab/mlint.vim
+++ b/ale_linters/matlab/mlint.vim
@@ -30,7 +30,7 @@ function! ale_linters#matlab#mlint#Handle(buffer, lines) abort
 
         " Suppress erroneous waring about filename
         " TODO: Enable this error when copying filename is supported
-        if l:code ==# 'FNDEF'
+        if l:code is# 'FNDEF'
             continue
         endif
 
diff --git a/ale_linters/nim/nimcheck.vim b/ale_linters/nim/nimcheck.vim
index 19e67303..e9576ff2 100644
--- a/ale_linters/nim/nimcheck.vim
+++ b/ale_linters/nim/nimcheck.vim
@@ -26,7 +26,7 @@ function! ale_linters#nim#nimcheck#Handle(buffer, lines) abort
 
         if len(l:textmatch) > 0
             let l:errortype = l:textmatch[1]
-            if l:errortype ==# 'Error'
+            if l:errortype is# 'Error'
                 let l:type = 'E'
             endif
         endif
diff --git a/ale_linters/perl/perlcritic.vim b/ale_linters/perl/perlcritic.vim
index a9e8f117..6f23048d 100644
--- a/ale_linters/perl/perlcritic.vim
+++ b/ale_linters/perl/perlcritic.vim
@@ -21,7 +21,7 @@ function! ale_linters#perl#perlcritic#GetProfile(buffer) abort
 
     " first see if we've been overridden
     let l:profile = ale#Var(a:buffer, 'perl_perlcritic_profile')
-    if l:profile ==? ''
+    if l:profile is? ''
         return ''
     endif
 
diff --git a/ale_linters/php/phpcs.vim b/ale_linters/php/phpcs.vim
index a8eae4e6..ddaf171e 100644
--- a/ale_linters/php/phpcs.vim
+++ b/ale_linters/php/phpcs.vim
@@ -40,7 +40,7 @@ function! ale_linters#php#phpcs#Handle(buffer, lines) abort
         \   'lnum': l:match[1] + 0,
         \   'col': l:match[2] + 0,
         \   'text': l:text,
-        \   'type': l:type ==# 'error' ? 'E' : 'W',
+        \   'type': l:type is# 'error' ? 'E' : 'W',
         \})
     endfor
 
diff --git a/ale_linters/python/flake8.vim b/ale_linters/python/flake8.vim
index bf7b3027..982a098e 100644
--- a/ale_linters/python/flake8.vim
+++ b/ale_linters/python/flake8.vim
@@ -115,7 +115,7 @@ function! ale_linters#python#flake8#Handle(buffer, lines) abort
     for l:match in ale#util#GetMatches(a:lines, l:pattern)
         let l:code = l:match[3]
 
-        if (l:code ==# 'W291' || l:code ==# 'W293')
+        if (l:code is# 'W291' || l:code is# 'W293')
         \ && !ale#Var(a:buffer, 'warn_about_trailing_whitespace')
             " Skip warnings for trailing whitespace if the option is off.
             continue
@@ -128,12 +128,12 @@ function! ale_linters#python#flake8#Handle(buffer, lines) abort
         \   'type': 'W',
         \}
 
-        if l:code[:0] ==# 'F' || l:code ==# 'E999'
+        if l:code[:0] is# 'F' || l:code is# 'E999'
             let l:item.type = 'E'
-        elseif l:code[:0] ==# 'E'
+        elseif l:code[:0] is# 'E'
             let l:item.type = 'E'
             let l:item.sub_type = 'style'
-        elseif l:code[:0] ==# 'W'
+        elseif l:code[:0] is# 'W'
             let l:item.sub_type = 'style'
         endif
 
diff --git a/ale_linters/python/pylint.vim b/ale_linters/python/pylint.vim
index 6f95776b..befc51a5 100644
--- a/ale_linters/python/pylint.vim
+++ b/ale_linters/python/pylint.vim
@@ -31,13 +31,13 @@ function! ale_linters#python#pylint#Handle(buffer, lines) abort
         "let l:failed = append(0, l:match)
         let l:code = l:match[3]
 
-        if (l:code ==# 'C0303')
+        if (l:code is# 'C0303')
         \ && !ale#Var(a:buffer, 'warn_about_trailing_whitespace')
             " Skip warnings for trailing whitespace if the option is off.
             continue
         endif
 
-        if l:code ==# 'I0011'
+        if l:code is# 'I0011'
             " Skip 'Locally disabling' message
              continue
         endif
@@ -46,7 +46,7 @@ function! ale_linters#python#pylint#Handle(buffer, lines) abort
         \   'lnum': l:match[1] + 0,
         \   'col': l:match[2] + 1,
         \   'text': l:code . ': ' . l:match[5] . ' (' . l:match[4] . ')',
-        \   'type': l:code[:0] ==# 'E' ? 'E' : 'W',
+        \   'type': l:code[:0] is# 'E' ? 'E' : 'W',
         \})
     endfor
 
diff --git a/ale_linters/ruby/brakeman.vim b/ale_linters/ruby/brakeman.vim
index 0070c15c..790eb563 100644
--- a/ale_linters/ruby/brakeman.vim
+++ b/ale_linters/ruby/brakeman.vim
@@ -33,7 +33,7 @@ endfunction
 function! ale_linters#ruby#brakeman#GetCommand(buffer) abort
     let l:rails_root = ale#ruby#FindRailsRoot(a:buffer)
 
-    if l:rails_root ==? ''
+    if l:rails_root is? ''
         return ''
     endif
 
diff --git a/ale_linters/ruby/rails_best_practices.vim b/ale_linters/ruby/rails_best_practices.vim
index 503a115c..107753c3 100644
--- a/ale_linters/ruby/rails_best_practices.vim
+++ b/ale_linters/ruby/rails_best_practices.vim
@@ -30,7 +30,7 @@ function! ale_linters#ruby#rails_best_practices#GetCommand(buffer) abort
 
     let l:rails_root = ale#ruby#FindRailsRoot(a:buffer)
 
-    if l:rails_root ==? ''
+    if l:rails_root is? ''
         return ''
     endif
 
diff --git a/ale_linters/ruby/rubocop.vim b/ale_linters/ruby/rubocop.vim
index 3d7b64d1..2a4388f2 100644
--- a/ale_linters/ruby/rubocop.vim
+++ b/ale_linters/ruby/rubocop.vim
@@ -43,9 +43,9 @@ function! ale_linters#ruby#rubocop#Handle(buffer, lines) abort
 endfunction
 
 function! ale_linters#ruby#rubocop#GetType(severity) abort
-    if a:severity ==? 'convention'
-    \|| a:severity ==? 'warning'
-    \|| a:severity ==? 'refactor'
+    if a:severity is? 'convention'
+    \|| a:severity is? 'warning'
+    \|| a:severity is? 'refactor'
         return 'W'
     endif
 
diff --git a/ale_linters/scala/scalac.vim b/ale_linters/scala/scalac.vim
index 9262e625..584aee74 100644
--- a/ale_linters/scala/scalac.vim
+++ b/ale_linters/scala/scalac.vim
@@ -38,7 +38,7 @@ function! ale_linters#scala#scalac#Handle(buffer, lines) abort
         endif
 
         let l:text = l:match[3]
-        let l:type = l:match[2] ==# 'error' ? 'E' : 'W'
+        let l:type = l:match[2] is# 'error' ? 'E' : 'W'
         let l:col = 0
 
         if l:ln + 1 < len(a:lines)
diff --git a/ale_linters/scss/scsslint.vim b/ale_linters/scss/scsslint.vim
index 2331ac16..7ce57241 100644
--- a/ale_linters/scss/scsslint.vim
+++ b/ale_linters/scss/scsslint.vim
@@ -19,7 +19,7 @@ function! ale_linters#scss#scsslint#Handle(buffer, lines) abort
         \   'lnum': l:match[1] + 0,
         \   'col': l:match[2] + 0,
         \   'text': l:match[4],
-        \   'type': l:match[3] ==# 'E' ? 'E' : 'W',
+        \   'type': l:match[3] is# 'E' ? 'E' : 'W',
         \})
     endfor
 
diff --git a/ale_linters/sh/shell.vim b/ale_linters/sh/shell.vim
index 1539e8b3..8f5ca3ae 100644
--- a/ale_linters/sh/shell.vim
+++ b/ale_linters/sh/shell.vim
@@ -11,7 +11,7 @@ endif
 if !exists('g:ale_sh_shell_default_shell')
     let g:ale_sh_shell_default_shell = fnamemodify($SHELL, ':t')
 
-    if g:ale_sh_shell_default_shell ==# '' || g:ale_sh_shell_default_shell ==# 'fish'
+    if g:ale_sh_shell_default_shell is# '' || g:ale_sh_shell_default_shell is# 'fish'
         let g:ale_sh_shell_default_shell = 'bash'
     endif
 endif
diff --git a/ale_linters/sml/smlnj.vim b/ale_linters/sml/smlnj.vim
index fda1d038..4acfc9e6 100644
--- a/ale_linters/sml/smlnj.vim
+++ b/ale_linters/sml/smlnj.vim
@@ -29,7 +29,7 @@ function! ale_linters#sml#smlnj#Handle(buffer, lines) abort
           \   'bufnr': a:buffer,
           \   'lnum': l:match[1] + 0,
           \   'text': l:match[2] . ': ' . l:match[3],
-          \   'type': l:match[2] ==# 'error' ? 'E' : 'W',
+          \   'type': l:match[2] is# 'error' ? 'E' : 'W',
           \})
           continue
         endif
diff --git a/ale_linters/tcl/nagelfar.vim b/ale_linters/tcl/nagelfar.vim
index 8b29f9ee..13b7a549 100644
--- a/ale_linters/tcl/nagelfar.vim
+++ b/ale_linters/tcl/nagelfar.vim
@@ -28,7 +28,7 @@ function! ale_linters#tcl#nagelfar#Handle(buffer, lines) abort
     for l:match in ale#util#GetMatches(a:lines, l:pattern)
         call add(l:output, {
         \   'lnum': l:match[1] + 0,
-        \   'type': l:match[2] ==# 'N' ? 'W' : l:match[2],
+        \   'type': l:match[2] is# 'N' ? 'W' : l:match[2],
         \   'text': l:match[3],
         \})
     endfor
diff --git a/ale_linters/typescript/tslint.vim b/ale_linters/typescript/tslint.vim
index 7cd1cb4b..cdc896e1 100644
--- a/ale_linters/typescript/tslint.vim
+++ b/ale_linters/typescript/tslint.vim
@@ -17,7 +17,7 @@ function! ale_linters#typescript#tslint#Handle(buffer, lines) abort
     for l:error in ale#util#FuzzyJSONDecode(a:lines, [])
         if ale#path#IsBufferPath(a:buffer, l:error.name)
             call add(l:output, {
-            \   'type': (get(l:error, 'ruleSeverity', '') ==# 'WARNING' ? 'W' : 'E'),
+            \   'type': (get(l:error, 'ruleSeverity', '') is# 'WARNING' ? 'W' : 'E'),
             \   'text': l:error.failure,
             \   'lnum': l:error.startPosition.line + 1,
             \   'col': l:error.startPosition.character + 1,
diff --git a/ale_linters/verilog/iverilog.vim b/ale_linters/verilog/iverilog.vim
index 0f4cd7b3..18769d56 100644
--- a/ale_linters/verilog/iverilog.vim
+++ b/ale_linters/verilog/iverilog.vim
@@ -14,7 +14,7 @@ function! ale_linters#verilog#iverilog#Handle(buffer, lines) abort
     for l:match in ale#util#GetMatches(a:lines, l:pattern)
         let l:line = l:match[1] + 0
         let l:type = l:match[2] =~# 'error' ? 'E' : 'W'
-        let l:text = l:match[2] ==# 'syntax error' ? 'syntax error' : l:match[4]
+        let l:text = l:match[2] is# 'syntax error' ? 'syntax error' : l:match[4]
 
         call add(l:output, {
         \   'lnum': l:line,
diff --git a/ale_linters/verilog/verilator.vim b/ale_linters/verilog/verilator.vim
index 9a0067e8..6053da09 100644
--- a/ale_linters/verilog/verilator.vim
+++ b/ale_linters/verilog/verilator.vim
@@ -33,7 +33,7 @@ function! ale_linters#verilog#verilator#Handle(buffer, lines) abort
 
     for l:match in ale#util#GetMatches(a:lines, l:pattern)
         let l:line = l:match[3] + 0
-        let l:type = l:match[1] ==# 'Error' ? 'E' : 'W'
+        let l:type = l:match[1] is# 'Error' ? 'E' : 'W'
         let l:text = l:match[4]
         let l:file = l:match[2]
 
diff --git a/ale_linters/yaml/swaglint.vim b/ale_linters/yaml/swaglint.vim
index 1368d7b7..454cad05 100644
--- a/ale_linters/yaml/swaglint.vim
+++ b/ale_linters/yaml/swaglint.vim
@@ -21,7 +21,7 @@ function! ale_linters#yaml#swaglint#Handle(buffer, lines) abort
 
     for l:match in ale#util#GetMatches(a:lines, l:pattern)
         let l:obj = {
-        \   'type': l:match[1] ==# 'error' ? 'E' : 'W',
+        \   'type': l:match[1] is# 'error' ? 'E' : 'W',
         \   'lnum': l:match[2] + 0,
         \   'col': l:match[3] + 0,
         \   'text': l:match[4],
diff --git a/ale_linters/yaml/yamllint.vim b/ale_linters/yaml/yamllint.vim
index a0eb2a0a..731f8012 100644
--- a/ale_linters/yaml/yamllint.vim
+++ b/ale_linters/yaml/yamllint.vim
@@ -33,7 +33,7 @@ function! ale_linters#yaml#yamllint#Handle(buffer, lines) abort
         \   'lnum': l:line,
         \   'col': l:col,
         \   'text': l:text,
-        \   'type': l:type ==# 'error' ? 'E' : 'W',
+        \   'type': l:type is# 'error' ? 'E' : 'W',
         \})
     endfor
 
diff --git a/autoload/ale.vim b/autoload/ale.vim
index aba3fda1..55125a04 100644
--- a/autoload/ale.vim
+++ b/autoload/ale.vim
@@ -50,7 +50,7 @@ function! ale#Queue(delay, ...) abort
 
     " Remember that we want to check files for this buffer.
     " We will remember this until we finally run the linters, via any event.
-    if l:linting_flag ==# 'lint_file'
+    if l:linting_flag is# 'lint_file'
         let s:should_lint_file_for_buffer[bufnr('%')] = 1
     endif
 
@@ -157,7 +157,7 @@ endfunction
 " Escape a string suitably for each platform.
 " shellescape does not work on Windows.
 function! ale#Escape(str) abort
-    if fnamemodify(&shell, ':t') ==? 'cmd.exe'
+    if fnamemodify(&shell, ':t') is? 'cmd.exe'
         " If the string contains spaces, it will be surrounded by quotes.
         " Otherwise, special characters will be escaped with carets (^).
         return substitute(
diff --git a/autoload/ale/c.vim b/autoload/ale/c.vim
index 1703da78..b9f94399 100644
--- a/autoload/ale/c.vim
+++ b/autoload/ale/c.vim
@@ -9,7 +9,7 @@ function! ale#c#FindProjectRoot(buffer) abort
             let l:path = fnamemodify(l:full_path, ':h')
 
             " Correct .git path detection.
-            if fnamemodify(l:path, ':t') ==# '.git'
+            if fnamemodify(l:path, ':t') is# '.git'
                 let l:path = fnamemodify(l:path, ':h')
             endif
 
diff --git a/autoload/ale/completion.vim b/autoload/ale/completion.vim
index eac6e6fc..df8134a4 100644
--- a/autoload/ale/completion.vim
+++ b/autoload/ale/completion.vim
@@ -44,7 +44,7 @@ function! ale#completion#FilterSuggestionsByPrefix(suggestions, prefix) abort
     "   foo.
     "       ^
     " We need to include all of the given suggestions.
-    if a:prefix ==# '.'
+    if a:prefix is# '.'
         return a:suggestions
     endif
 
@@ -59,7 +59,7 @@ function! ale#completion#FilterSuggestionsByPrefix(suggestions, prefix) abort
     for l:suggestion in a:suggestions
         " Add suggestions if the suggestion starts with a case-insensitive
         " match for the prefix.
-        if l:suggestion.word[: len(a:prefix) - 1] ==? a:prefix
+        if l:suggestion.word[: len(a:prefix) - 1] is? a:prefix
             call add(l:filtered_suggestions, l:suggestion)
         endif
     endfor
@@ -150,9 +150,9 @@ function! ale#completion#ParseTSServerCompletionEntryDetails(response) abort
             call add(l:documentationParts, l:part.text)
         endfor
 
-        if l:suggestion.kind ==# 'clasName'
+        if l:suggestion.kind is# 'clasName'
             let l:kind = 'f'
-        elseif l:suggestion.kind ==# 'parameterName'
+        elseif l:suggestion.kind is# 'parameterName'
             let l:kind = 'f'
         else
             let l:kind = 'v'
@@ -182,7 +182,7 @@ function! s:HandleTSServerLSPResponse(conn_id, response) abort
 
     let l:command = get(a:response, 'command', '')
 
-    if l:command ==# 'completions'
+    if l:command is# 'completions'
         let l:names = ale#completion#ParseTSServerCompletions(a:response)
 
         if !empty(l:names)
@@ -196,7 +196,7 @@ function! s:HandleTSServerLSPResponse(conn_id, response) abort
             \   ),
             \)
         endif
-    elseif l:command ==# 'completionEntryDetails'
+    elseif l:command is# 'completionEntryDetails'
         call ale#completion#Show(
         \   a:response,
         \   'ale#completion#ParseTSServerCompletionEntryDetails',
@@ -256,7 +256,7 @@ function! ale#completion#GetCompletions() abort
     \}
 
     for l:linter in ale#linter#Get(&filetype)
-        if l:linter.lsp ==# 'tsserver'
+        if l:linter.lsp is# 'tsserver'
             call s:GetLSPCompletions(l:linter)
         endif
     endfor
diff --git a/autoload/ale/cursor.vim b/autoload/ale/cursor.vim
index 85881c09..d30b1ebd 100644
--- a/autoload/ale/cursor.vim
+++ b/autoload/ale/cursor.vim
@@ -4,7 +4,7 @@
 " Return a formatted message according to g:ale_echo_msg_format variable
 function! s:GetMessage(linter, type, text) abort
     let l:msg = g:ale_echo_msg_format
-    let l:type = a:type ==# 'E'
+    let l:type = a:type is# 'E'
     \   ? g:ale_echo_msg_error_str
     \   : g:ale_echo_msg_warning_str
 
@@ -22,12 +22,12 @@ function! s:EchoWithShortMess(setting, message) abort
 
     try
         " Turn shortmess on or off.
-        if a:setting ==# 'on'
+        if a:setting is# 'on'
             setlocal shortmess+=T
             " echomsg is needed for the message to get truncated and appear in
             " the message history.
             exec "norm! :echomsg a:message\n"
-        elseif a:setting ==# 'off'
+        elseif a:setting is# 'off'
             setlocal shortmess-=T
             " Regular echo is needed for printing newline characters.
             echo a:message
diff --git a/autoload/ale/debugging.vim b/autoload/ale/debugging.vim
index 8136fbee..80d253e1 100644
--- a/autoload/ale/debugging.vim
+++ b/autoload/ale/debugging.vim
@@ -81,7 +81,7 @@ function! s:EchoCommandHistory() abort
         let l:status_message = l:item.status
 
         " Include the exit code in output if we have it.
-        if l:item.status ==# 'finished'
+        if l:item.status is# 'finished'
             let l:status_message .= ' - exit code ' . l:item.exit_code
         endif
 
diff --git a/autoload/ale/engine.vim b/autoload/ale/engine.vim
index 75f3088b..40cc7ad3 100644
--- a/autoload/ale/engine.vim
+++ b/autoload/ale/engine.vim
@@ -224,7 +224,7 @@ function! s:HandleTSServerDiagnostics(response, error_type) abort
     " tsserver sends syntax and semantic errors in separate messages, so we
     " have to collect the messages separately for each buffer and join them
     " back together again.
-    if a:error_type ==# 'syntax'
+    if a:error_type is# 'syntax'
         let l:info.syntax_loclist = l:thislist
     else
         let l:info.semantic_loclist = l:thislist
@@ -247,16 +247,16 @@ endfunction
 function! ale#engine#HandleLSPResponse(conn_id, response) abort
     let l:method = get(a:response, 'method', '')
 
-    if get(a:response, 'jsonrpc', '') ==# '2.0' && has_key(a:response, 'error')
+    if get(a:response, 'jsonrpc', '') is# '2.0' && has_key(a:response, 'error')
         " Uncomment this line to print LSP error messages.
         " call s:HandleLSPErrorMessage(a:response.error.message)
-    elseif l:method ==# 'textDocument/publishDiagnostics'
+    elseif l:method is# 'textDocument/publishDiagnostics'
         call s:HandleLSPDiagnostics(a:conn_id, a:response)
-    elseif get(a:response, 'type', '') ==# 'event'
-    \&& get(a:response, 'event', '') ==# 'semanticDiag'
+    elseif get(a:response, 'type', '') is# 'event'
+    \&& get(a:response, 'event', '') is# 'semanticDiag'
         call s:HandleTSServerDiagnostics(a:response, 'semantic')
-    elseif get(a:response, 'type', '') ==# 'event'
-    \&& get(a:response, 'event', '') ==# 'syntaxDiag'
+    elseif get(a:response, 'type', '') is# 'event'
+    \&& get(a:response, 'event', '') is# 'syntaxDiag'
         call s:HandleTSServerDiagnostics(a:response, 'syntax')
     endif
 endfunction
@@ -313,17 +313,17 @@ endfunction
 function! s:RemapItemTypes(type_map, loclist) abort
     for l:item in a:loclist
         let l:key = l:item.type
-        \   . (get(l:item, 'sub_type', '') ==# 'style' ? 'S' : '')
+        \   . (get(l:item, 'sub_type', '') is# 'style' ? 'S' : '')
         let l:new_key = get(a:type_map, l:key, '')
 
-        if l:new_key ==# 'E'
-        \|| l:new_key ==# 'ES'
-        \|| l:new_key ==# 'W'
-        \|| l:new_key ==# 'WS'
-        \|| l:new_key ==# 'I'
+        if l:new_key is# 'E'
+        \|| l:new_key is# 'ES'
+        \|| l:new_key is# 'W'
+        \|| l:new_key is# 'WS'
+        \|| l:new_key is# 'I'
             let l:item.type = l:new_key[0]
 
-            if l:new_key ==# 'ES' || l:new_key ==# 'WS'
+            if l:new_key is# 'ES' || l:new_key is# 'WS'
                 let l:item.sub_type = 'style'
             elseif has_key(l:item, 'sub_type')
                 call remove(l:item, 'sub_type')
@@ -465,9 +465,9 @@ function! s:RunJob(options) abort
     \   'exit_cb': function('s:HandleExit'),
     \}
 
-    if l:output_stream ==# 'stderr'
+    if l:output_stream is# 'stderr'
         let l:job_options.err_cb = function('s:GatherOutput')
-    elseif l:output_stream ==# 'both'
+    elseif l:output_stream is# 'both'
         let l:job_options.out_cb = function('s:GatherOutput')
         let l:job_options.err_cb = function('s:GatherOutput')
     else
@@ -635,7 +635,7 @@ function! s:CheckWithLSP(buffer, linter) abort
     " Remember the linter this connection is for.
     let s:lsp_linter_map[l:id] = a:linter.name
 
-    let l:change_message = a:linter.lsp ==# 'tsserver'
+    let l:change_message = a:linter.lsp is# 'tsserver'
     \   ? ale#lsp#tsserver_message#Geterr(a:buffer)
     \   : ale#lsp#message#DidChange(a:buffer)
     let l:request_id = ale#lsp#Send(l:id, l:change_message, l:root)
diff --git a/autoload/ale/fix.vim b/autoload/ale/fix.vim
index 73992125..3669fcd8 100644
--- a/autoload/ale/fix.vim
+++ b/autoload/ale/fix.vim
@@ -186,9 +186,9 @@ function! s:RunJob(options) abort
     if l:read_temporary_file
         " TODO: Check that a temporary file is set here.
         let l:job_info.file_to_read = l:temporary_file
-    elseif l:output_stream ==# 'stderr'
+    elseif l:output_stream is# 'stderr'
         let l:job_options.err_cb = function('s:GatherOutput')
-    elseif l:output_stream ==# 'both'
+    elseif l:output_stream is# 'both'
         let l:job_options.out_cb = function('s:GatherOutput')
         let l:job_options.err_cb = function('s:GatherOutput')
     else
@@ -320,7 +320,7 @@ function! ale#fix#InitBufferData(buffer, fixing_flag) abort
     \   'lines_before': getbufline(a:buffer, 1, '$'),
     \   'filename': expand('#' . a:buffer . ':p'),
     \   'done': 0,
-    \   'should_save': a:fixing_flag ==# 'save_file',
+    \   'should_save': a:fixing_flag is# 'save_file',
     \   'temporary_directory_list': [],
     \}
 endfunction
@@ -342,7 +342,7 @@ function! ale#fix#Fix(...) abort
     let l:callback_list = s:GetCallbacks()
 
     if empty(l:callback_list)
-        if l:fixing_flag ==# ''
+        if l:fixing_flag is# ''
             echoerr 'No fixers have been defined. Try :ALEFixSuggest'
         endif
 
diff --git a/autoload/ale/handlers/cppcheck.vim b/autoload/ale/handlers/cppcheck.vim
index b365c794..dc56cd0b 100644
--- a/autoload/ale/handlers/cppcheck.vim
+++ b/autoload/ale/handlers/cppcheck.vim
@@ -11,7 +11,7 @@ function! ale#handlers#cppcheck#HandleCppCheckFormat(buffer, lines) abort
         if ale#path#IsBufferPath(a:buffer, l:match[1])
             call add(l:output, {
             \   'lnum': str2nr(l:match[2]),
-            \   'type': l:match[3] ==# 'error' ? 'E' : 'W',
+            \   'type': l:match[3] is# 'error' ? 'E' : 'W',
             \   'text': l:match[4],
             \})
         endif
diff --git a/autoload/ale/handlers/css.vim b/autoload/ale/handlers/css.vim
index 71eaf2ce..4c1b81cb 100644
--- a/autoload/ale/handlers/css.vim
+++ b/autoload/ale/handlers/css.vim
@@ -29,7 +29,7 @@ function! ale#handlers#css#HandleCSSLintFormat(buffer, lines) abort
         \   'lnum': l:match[1] + 0,
         \   'col': l:match[2] + 0,
         \   'text': l:text,
-        \   'type': l:type ==# 'Warning' ? 'W' : 'E',
+        \   'type': l:type is# 'Warning' ? 'W' : 'E',
         \})
     endfor
 
@@ -61,7 +61,7 @@ function! ale#handlers#css#HandleStyleLintFormat(buffer, lines) abort
         call add(l:output, {
         \   'lnum': l:match[1] + 0,
         \   'col': l:match[2] + 0,
-        \   'type': l:match[3] ==# '✖' ? 'E' : 'W',
+        \   'type': l:match[3] is# '✖' ? 'E' : 'W',
         \   'text': l:match[4] . ' [' . l:match[5] . ']',
         \})
     endfor
diff --git a/autoload/ale/handlers/eslint.vim b/autoload/ale/handlers/eslint.vim
index a7ff0ae2..a5210ae0 100644
--- a/autoload/ale/handlers/eslint.vim
+++ b/autoload/ale/handlers/eslint.vim
@@ -92,7 +92,7 @@ function! ale#handlers#eslint#Handle(buffer, lines) abort
         \   'lnum': l:match[1] + 0,
         \   'col': l:match[2] + 0,
         \   'text': l:text,
-        \   'type': l:type ==# 'Warning' ? 'W' : 'E',
+        \   'type': l:type is# 'Warning' ? 'W' : 'E',
         \}
 
         for l:col_match in ale#util#GetMatches(l:text, s:col_end_patterns)
diff --git a/autoload/ale/handlers/gcc.vim b/autoload/ale/handlers/gcc.vim
index aaac5281..ad5cab39 100644
--- a/autoload/ale/handlers/gcc.vim
+++ b/autoload/ale/handlers/gcc.vim
@@ -81,7 +81,7 @@ function! ale#handlers#gcc#HandleGCCFormat(buffer, lines) abort
                 let l:included_filename = ''
             endif
         elseif l:include_lnum > 0
-        \&& (empty(l:included_filename) || l:included_filename ==# l:match[1])
+        \&& (empty(l:included_filename) || l:included_filename is# l:match[1])
             " If we hit the first error after an include header, or the
             " errors below have the same name as the first filename we see,
             " then include these lines, and remember what that filename was.
@@ -96,7 +96,7 @@ function! ale#handlers#gcc#HandleGCCFormat(buffer, lines) abort
             let l:included_filename = ''
 
             if s:IsHeaderFile(bufname(bufnr('')))
-            \&& l:match[5][:len(s:pragma_error) - 1] ==# s:pragma_error
+            \&& l:match[5][:len(s:pragma_error) - 1] is# s:pragma_error
                 continue
             endif
 
diff --git a/autoload/ale/handlers/haskell.vim b/autoload/ale/handlers/haskell.vim
index 5d417c89..bac5f4ae 100644
--- a/autoload/ale/handlers/haskell.vim
+++ b/autoload/ale/handlers/haskell.vim
@@ -14,7 +14,7 @@ function! ale#handlers#haskell#HandleGHCFormat(buffer, lines) abort
     for l:line in a:lines
         if len(matchlist(l:line, l:pattern)) > 0
             call add(l:corrected_lines, l:line)
-        elseif l:line ==# ''
+        elseif l:line is# ''
             call add(l:corrected_lines, l:line)
         else
             if len(l:corrected_lines) > 0
@@ -42,10 +42,10 @@ function! ale#handlers#haskell#HandleGHCFormat(buffer, lines) abort
           let l:text = l:errors[2]
         else
           let l:ghc_type = ''
-          let l:text = l:match[4][:0] ==# ' ' ? l:match[4][1:] : l:match[4]
+          let l:text = l:match[4][:0] is# ' ' ? l:match[4][1:] : l:match[4]
         endif
 
-        if l:ghc_type ==? 'Warning'
+        if l:ghc_type is? 'Warning'
             let l:type = 'W'
         else
             let l:type = 'E'
diff --git a/autoload/ale/handlers/rust.vim b/autoload/ale/handlers/rust.vim
index 3f9083a5..12a5a16a 100644
--- a/autoload/ale/handlers/rust.vim
+++ b/autoload/ale/handlers/rust.vim
@@ -47,7 +47,7 @@ function! ale#handlers#rust#HandleRustErrorsForFile(buffer, full_filename, lines
         for l:span in l:error.spans
             if (
             \   l:span.is_primary
-            \   && (ale#path#IsBufferPath(a:buffer, l:span.file_name) || l:span.file_name ==# '<anon>')
+            \   && (ale#path#IsBufferPath(a:buffer, l:span.file_name) || l:span.file_name is# '<anon>')
             \)
                 call add(l:output, {
                 \   'lnum': l:span.line_start,
diff --git a/autoload/ale/highlight.vim b/autoload/ale/highlight.vim
index a109a265..5c01e7a9 100644
--- a/autoload/ale/highlight.vim
+++ b/autoload/ale/highlight.vim
@@ -65,15 +65,15 @@ function! ale#highlight#UpdateHighlights() abort
     call ale#highlight#RemoveHighlights()
 
     for l:item in l:item_list
-        if l:item.type ==# 'W'
-            if get(l:item, 'sub_type', '') ==# 'style'
+        if l:item.type is# 'W'
+            if get(l:item, 'sub_type', '') is# 'style'
                 let l:group = 'ALEStyleWarning'
             else
                 let l:group = 'ALEWarning'
             endif
-        elseif l:item.type ==# 'I'
+        elseif l:item.type is# 'I'
             let l:group = 'ALEInfo'
-        elseif get(l:item, 'sub_type', '') ==# 'style'
+        elseif get(l:item, 'sub_type', '') is# 'style'
             let l:group = 'ALEStyleError'
         else
             let l:group = 'ALEError'
diff --git a/autoload/ale/job.vim b/autoload/ale/job.vim
index 93f28824..63cb8abc 100644
--- a/autoload/ale/job.vim
+++ b/autoload/ale/job.vim
@@ -34,7 +34,7 @@ function! ale#job#JoinNeovimOutput(job, last_line, data, mode, callback) abort
         let l:new_last_line = a:last_line . a:data[0]
     endif
 
-    if a:mode ==# 'raw'
+    if a:mode is# 'raw'
         if !empty(l:lines)
             call a:callback(a:job, join(l:lines, "\n") . "\n")
         endif
@@ -50,7 +50,7 @@ endfunction
 function! s:NeoVimCallback(job, data, event) abort
     let l:info = s:job_map[a:job]
 
-    if a:event ==# 'stdout'
+    if a:event is# 'stdout'
         let l:info.out_cb_line = ale#job#JoinNeovimOutput(
         \   a:job,
         \   l:info.out_cb_line,
@@ -58,7 +58,7 @@ function! s:NeoVimCallback(job, data, event) abort
         \   l:info.mode,
         \   ale#util#GetFunction(l:info.out_cb),
         \)
-    elseif a:event ==# 'stderr'
+    elseif a:event is# 'stderr'
         let l:info.err_cb_line = ale#job#JoinNeovimOutput(
         \   a:job,
         \   l:info.err_cb_line,
@@ -117,7 +117,7 @@ function! s:VimCloseCallback(channel) abort
 
     " job_status() can trigger the exit handler.
     " The channel can close before the job has exited.
-    if job_status(l:job) ==# 'dead'
+    if job_status(l:job) is# 'dead'
         try
             if !empty(l:info) && has_key(l:info, 'exit_cb')
                 call ale#util#GetFunction(l:info.exit_cb)(l:job_id, l:info.exit_code)
@@ -142,7 +142,7 @@ function! s:VimExitCallback(job, exit_code) abort
     let l:info.exit_code = a:exit_code
 
     " The program can exit before the data has finished being read.
-    if ch_status(job_getchannel(a:job)) ==# 'closed'
+    if ch_status(job_getchannel(a:job)) is# 'closed'
         try
             if !empty(l:info) && has_key(l:info, 'exit_cb')
                 call ale#util#GetFunction(l:info.exit_cb)(l:job_id, a:exit_code)
@@ -273,7 +273,7 @@ function! ale#job#IsRunning(job_id) abort
         endtry
     elseif has_key(s:job_map, a:job_id)
         let l:job = s:job_map[a:job_id].job
-        return job_status(l:job) ==# 'run'
+        return job_status(l:job) is# 'run'
     endif
 
     return 0
@@ -296,7 +296,7 @@ function! ale#job#Stop(job_id) abort
 
         " We must close the channel for reading the buffer if it is open
         " when stopping a job. Otherwise, we will get errors in the status line.
-        if ch_status(job_getchannel(l:job)) ==# 'open'
+        if ch_status(job_getchannel(l:job)) is# 'open'
             call ch_close_in(job_getchannel(l:job))
         endif
 
diff --git a/autoload/ale/linter.vim b/autoload/ale/linter.vim
index 8fc68510..7c6f08f8 100644
--- a/autoload/ale/linter.vim
+++ b/autoload/ale/linter.vim
@@ -59,7 +59,7 @@ function! ale#linter#PreProcess(linter) abort
         throw '`name` must be defined to name the linter'
     endif
 
-    let l:needs_address = l:obj.lsp ==# 'socket'
+    let l:needs_address = l:obj.lsp is# 'socket'
     let l:needs_executable = l:obj.lsp !=# 'socket'
     let l:needs_command = l:obj.lsp !=# 'socket'
     let l:needs_lsp_details = !empty(l:obj.lsp)
@@ -311,7 +311,7 @@ function! ale#linter#Get(original_filetypes) abort
         let l:all_linters = ale#linter#GetAll(l:filetype)
         let l:filetype_linters = []
 
-        if type(l:linter_names) == type('') && l:linter_names ==# 'all'
+        if type(l:linter_names) == type('') && l:linter_names is# 'all'
             let l:filetype_linters = l:all_linters
         elseif type(l:linter_names) == type([])
             " Select only the linters we or the user has specified.
@@ -383,7 +383,7 @@ function! ale#linter#StartLSP(buffer, linter, callback) abort
         return {}
     endif
 
-    if a:linter.lsp ==# 'socket'
+    if a:linter.lsp is# 'socket'
         let l:address = ale#linter#GetAddress(a:buffer, a:linter)
         let l:conn_id = ale#lsp#ConnectToAddress(
         \   l:address,
@@ -425,7 +425,7 @@ function! ale#linter#StartLSP(buffer, linter, callback) abort
     endif
 
     " The change message needs to be sent for tsserver before doing anything.
-    if a:linter.lsp ==# 'tsserver'
+    if a:linter.lsp is# 'tsserver'
         call ale#lsp#Send(l:conn_id, ale#lsp#tsserver_message#Change(a:buffer))
     endif
 
diff --git a/autoload/ale/list.vim b/autoload/ale/list.vim
index ae13e10a..1311bef3 100644
--- a/autoload/ale/list.vim
+++ b/autoload/ale/list.vim
@@ -4,7 +4,7 @@
 " Return 1 if there is a buffer with buftype == 'quickfix' in bufffer list
 function! ale#list#IsQuickfixOpen() abort
     for l:buf in range(1, bufnr('$'))
-        if getbufvar(l:buf, '&buftype') ==# 'quickfix'
+        if getbufvar(l:buf, '&buftype') is# 'quickfix'
             return 1
         endif
     endfor
@@ -18,7 +18,7 @@ function! s:ShouldOpen(buffer) abort
     let l:saved = getbufvar(a:buffer, 'ale_save_event_fired', 0)
 
     return (type(l:val) == type(1) && l:val == 1)
-    \   || (type(l:val) == type('') && l:val ==# 'on_save' && l:saved)
+    \   || (type(l:val) == type('') && l:val is# 'on_save' && l:saved)
 endfunction
 
 function! ale#list#SetLists(buffer, loclist) abort
@@ -51,8 +51,8 @@ function! ale#list#SetLists(buffer, loclist) abort
     if s:ShouldOpen(a:buffer) && (l:keep_open || !empty(a:loclist))
         let l:winnr = winnr()
         let l:mode = mode()
-        let l:reset_visual_selection = l:mode ==? 'v' || l:mode ==# "\<c-v>"
-        let l:reset_character_selection = l:mode ==? 's' || l:mode ==# "\<c-s>"
+        let l:reset_visual_selection = l:mode is? 'v' || l:mode is# "\<c-v>"
+        let l:reset_character_selection = l:mode is? 's' || l:mode is# "\<c-s>"
 
         if g:ale_set_quickfix
             if !ale#list#IsQuickfixOpen()
diff --git a/autoload/ale/loclist_jumping.vim b/autoload/ale/loclist_jumping.vim
index 88ed4c97..f967e2b0 100644
--- a/autoload/ale/loclist_jumping.vim
+++ b/autoload/ale/loclist_jumping.vim
@@ -17,7 +17,7 @@ function! ale#loclist_jumping#FindNearest(direction, wrap) abort
     let l:search_item = {'lnum': l:pos[1], 'col': l:pos[2]}
 
     " When searching backwards, so we can find the next smallest match.
-    if a:direction ==# 'before'
+    if a:direction is# 'before'
         let l:loclist = reverse(copy(l:loclist))
     endif
 
@@ -36,11 +36,11 @@ function! ale#loclist_jumping#FindNearest(direction, wrap) abort
         \   l:search_item
         \)
 
-        if a:direction ==# 'before' && l:cmp_value < 0
+        if a:direction is# 'before' && l:cmp_value < 0
             return [l:item.lnum, l:item.col]
         endif
 
-        if a:direction ==# 'after' && l:cmp_value > 0
+        if a:direction is# 'after' && l:cmp_value > 0
             return [l:item.lnum, l:item.col]
         endif
     endfor
diff --git a/autoload/ale/lsp.vim b/autoload/ale/lsp.vim
index bb9a24f2..ef09dded 100644
--- a/autoload/ale/lsp.vim
+++ b/autoload/ale/lsp.vim
@@ -190,17 +190,17 @@ function! ale#lsp#HandleOtherInitializeResponses(conn, response) abort
         return
     endif
 
-    if get(a:response, 'method', '') ==# ''
+    if get(a:response, 'method', '') is# ''
         if has_key(get(a:response, 'result', {}), 'capabilities')
             for [l:dir, l:project] in l:uninitialized_projects
                 call s:MarkProjectAsInitialized(a:conn, l:project)
             endfor
         endif
-    elseif get(a:response, 'method', '') ==# 'textDocument/publishDiagnostics'
+    elseif get(a:response, 'method', '') is# 'textDocument/publishDiagnostics'
         let l:filename = ale#path#FromURI(a:response.params.uri)
 
         for [l:dir, l:project] in l:uninitialized_projects
-            if l:filename[:len(l:dir) - 1] ==# l:dir
+            if l:filename[:len(l:dir) - 1] is# l:dir
                 call s:MarkProjectAsInitialized(a:conn, l:project)
             endif
         endfor
@@ -215,7 +215,7 @@ function! ale#lsp#HandleMessage(conn, message) abort
 
     " Call our callbacks.
     for l:response in l:response_list
-        if get(l:response, 'method', '') ==# 'initialize'
+        if get(l:response, 'method', '') is# 'initialize'
             call s:HandleInitializeResponse(a:conn, l:response)
         else
             call ale#lsp#HandleOtherInitializeResponses(a:conn, l:response)
@@ -304,7 +304,7 @@ function! ale#lsp#ConnectToAddress(address, project_root, callback) abort
         \})
     endif
 
-    if ch_status(l:conn.channnel) ==# 'fail'
+    if ch_status(l:conn.channnel) is# 'fail'
         return 0
     endif
 
@@ -319,7 +319,7 @@ endfunction
 function! s:SendMessageData(conn, data) abort
     if has_key(a:conn, 'executable')
         call ale#job#SendRaw(a:conn.id, a:data)
-    elseif has_key(a:conn, 'channel') && ch_status(a:conn.channnel) ==# 'open'
+    elseif has_key(a:conn, 'channel') && ch_status(a:conn.channnel) is# 'open'
         " Send the message to the server
         call ch_sendraw(a:conn.channel, a:data)
     else
diff --git a/autoload/ale/path.vim b/autoload/ale/path.vim
index c68114ae..49069478 100644
--- a/autoload/ale/path.vim
+++ b/autoload/ale/path.vim
@@ -65,7 +65,7 @@ endfunction
 " Return 1 if a path is an absolute path.
 function! ale#path#IsAbsolute(filename) abort
     " Check for /foo and C:\foo, etc.
-    return a:filename[:0] ==# '/' || a:filename[1:2] ==# ':\'
+    return a:filename[:0] is# '/' || a:filename[1:2] is# ':\'
 endfunction
 
 " Given a filename, return 1 if the file represents some temporary file
@@ -78,7 +78,7 @@ function! ale#path#IsTempName(filename) abort
     \]
 
     for l:prefix in l:prefix_list
-        if a:filename[:len(l:prefix) - 1] ==# l:prefix
+        if a:filename[:len(l:prefix) - 1] is# l:prefix
             return 1
         endif
     endfor
@@ -90,19 +90,19 @@ endfunction
 " two paths represent the same file on disk.
 function! ale#path#IsBufferPath(buffer, complex_filename) abort
     " If the path is one of many different names for stdin, we have a match.
-    if a:complex_filename ==# '-'
-    \|| a:complex_filename ==# 'stdin'
-    \|| a:complex_filename[:0] ==# '<'
+    if a:complex_filename is# '-'
+    \|| a:complex_filename is# 'stdin'
+    \|| a:complex_filename[:0] is# '<'
         return 1
     endif
 
     let l:test_filename = ale#path#Simplify(a:complex_filename)
 
-    if l:test_filename[:1] ==# './'
+    if l:test_filename[:1] is# './'
         let l:test_filename = l:test_filename[2:]
     endif
 
-    if l:test_filename[:1] ==# '..'
+    if l:test_filename[:1] is# '..'
         " Remove ../../ etc. from the front of the path.
         let l:test_filename = substitute(l:test_filename, '\v^(\.\.[/\\])+', '/', '')
     endif
@@ -114,8 +114,8 @@ function! ale#path#IsBufferPath(buffer, complex_filename) abort
 
     let l:buffer_filename = expand('#' . a:buffer . ':p')
 
-    return l:buffer_filename ==# l:test_filename
-    \   || l:buffer_filename[-len(l:test_filename):] ==# l:test_filename
+    return l:buffer_filename is# l:test_filename
+    \   || l:buffer_filename[-len(l:test_filename):] is# l:test_filename
 endfunction
 
 " Given a path, return every component of the path, moving upwards.
@@ -133,7 +133,7 @@ function! ale#path#Upwards(path) abort
     if ale#Has('win32') && a:path =~# '^[a-zA-z]:\'
         " Add \ to C: for C:\, etc.
         let l:path_list[-1] .= '\'
-    elseif a:path[0] ==# '/'
+    elseif a:path[0] is# '/'
         " If the path starts with /, even on Windows, add / and / to all paths.
         call map(l:path_list, '''/'' . v:val')
         call add(l:path_list, '/')
@@ -146,10 +146,10 @@ endfunction
 " relatives paths will not be prefixed with the protocol.
 " For Windows paths, the `:` in C:\ etc. will not be percent-encoded.
 function! ale#path#ToURI(path) abort
-    let l:has_drive_letter = a:path[1:2] ==# ':\'
+    let l:has_drive_letter = a:path[1:2] is# ':\'
 
     return substitute(
-    \   ((l:has_drive_letter || a:path[:0] ==# '/') ? 'file://' : '')
+    \   ((l:has_drive_letter || a:path[:0] is# '/') ? 'file://' : '')
     \       . (l:has_drive_letter ? '/' . a:path[:2] : '')
     \       . ale#uri#Encode(l:has_drive_letter ? a:path[3:] : a:path),
     \   '\\',
@@ -160,7 +160,7 @@ endfunction
 
 function! ale#path#FromURI(uri) abort
     let l:i = len('file://')
-    let l:encoded_path = a:uri[: l:i - 1] ==# 'file://' ? a:uri[l:i :] : a:uri
+    let l:encoded_path = a:uri[: l:i - 1] is# 'file://' ? a:uri[l:i :] : a:uri
 
     return ale#uri#Decode(l:encoded_path)
 endfunction
diff --git a/autoload/ale/pattern_options.vim b/autoload/ale/pattern_options.vim
index 03c9146a..a603c980 100644
--- a/autoload/ale/pattern_options.vim
+++ b/autoload/ale/pattern_options.vim
@@ -13,7 +13,7 @@ function! ale#pattern_options#SetOptions() abort
     endfor
 
     for l:key in keys(l:options)
-        if l:key[:0] ==# '&'
+        if l:key[:0] is# '&'
             call setbufvar(bufnr(''), l:key, l:options[l:key])
         else
             let b:[l:key] = l:options[l:key]
diff --git a/autoload/ale/sign.vim b/autoload/ale/sign.vim
index 37105f9f..222fa6b7 100644
--- a/autoload/ale/sign.vim
+++ b/autoload/ale/sign.vim
@@ -168,9 +168,9 @@ function! ale#sign#GetSignType(sublist) abort
     let l:highest_level = 100
 
     for l:item in a:sublist
-        let l:level = (l:item.type ==# 'I' ? 2 : l:item.type ==# 'W')
+        let l:level = (l:item.type is# 'I' ? 2 : l:item.type is# 'W')
 
-        if get(l:item, 'sub_type', '') ==# 'style'
+        if get(l:item, 'sub_type', '') is# 'style'
             let l:level += 10
         endif
 
diff --git a/autoload/ale/statusline.vim b/autoload/ale/statusline.vim
index afc27b3b..fd586a23 100644
--- a/autoload/ale/statusline.vim
+++ b/autoload/ale/statusline.vim
@@ -26,15 +26,15 @@ function! ale#statusline#Update(buffer, loclist) abort
     let l:count.total = len(a:loclist)
 
     for l:entry in a:loclist
-        if l:entry.type ==# 'W'
-            if get(l:entry, 'sub_type', '') ==# 'style'
+        if l:entry.type is# 'W'
+            if get(l:entry, 'sub_type', '') is# 'style'
                 let l:count.style_warning += 1
             else
                 let l:count.warning += 1
             endif
-        elseif l:entry.type ==# 'I'
+        elseif l:entry.type is# 'I'
             let l:count.info += 1
-        elseif get(l:entry, 'sub_type', '') ==# 'style'
+        elseif get(l:entry, 'sub_type', '') is# 'style'
             let l:count.style_error += 1
         else
             let l:count.error += 1
diff --git a/autoload/ale/util.vim b/autoload/ale/util.vim
index 312f8f0f..37c6f10f 100644
--- a/autoload/ale/util.vim
+++ b/autoload/ale/util.vim
@@ -193,7 +193,7 @@ endfunction
 " The buffer number is required for determining the fileformat setting for
 " the buffer.
 function! ale#util#Writefile(buffer, lines, filename) abort
-    let l:corrected_lines = getbufvar(a:buffer, '&fileformat') ==# 'dos'
+    let l:corrected_lines = getbufvar(a:buffer, '&fileformat') is# 'dos'
     \   ? map(copy(a:lines), 'v:val . "\r"')
     \   : a:lines
 
diff --git a/custom-checks b/custom-checks
index 3bb60cda..9a61eeed 100755
--- a/custom-checks
+++ b/custom-checks
@@ -65,6 +65,8 @@ if (( FIX_ERRORS )); then
     for directory in "${directories[@]}"; do
         sed -i "s/^\(function.*)\) *$/\1 abort/" "$directory"/**/*.vim
         sed -i "s/shellescape(/ale#Escape(/" "$directory"/**/*.vim
+        sed -i 's/==#/is#/g' "$directory"/**/*.vim
+        sed -i 's/==?/is?/g' "$directory"/**/*.vim
     done
 fi
 
@@ -80,5 +82,7 @@ check_errors 'let g:ale_\w\+_\w\+_args =' 'Name your option g:ale_<filetype>_<li
 check_errors 'shellescape(' 'Use ale#Escape instead of shellescape'
 check_errors 'simplify(' 'Use ale#path#Simplify instead of simplify'
 check_errors "expand(['\"]%" "Use expand('#' . a:buffer . '...') instead. You might get a filename for the wrong buffer."
+check_errors '==#' "Use 'is#' instead of '==#'. 0 ==# 'foobar' is true"
+check_errors '==?' "Use 'is?' instead of '==?'. 0 ==? 'foobar' is true"
 
 exit $RETURN_CODE
diff --git a/plugin/ale.vim b/plugin/ale.vim
index 79e6836b..6b8b6ec3 100644
--- a/plugin/ale.vim
+++ b/plugin/ale.vim
@@ -206,11 +206,11 @@ function! ALEInitAuGroups() abort
     augroup ALERunOnTextChangedGroup
         autocmd!
         if g:ale_enabled
-            if l:text_changed ==? 'always' || l:text_changed ==# '1'
+            if l:text_changed is? 'always' || l:text_changed is# '1'
                 autocmd TextChanged,TextChangedI * call ale#Queue(g:ale_lint_delay)
-            elseif l:text_changed ==? 'normal'
+            elseif l:text_changed is? 'normal'
                 autocmd TextChanged * call ale#Queue(g:ale_lint_delay)
-            elseif l:text_changed ==? 'insert'
+            elseif l:text_changed is? 'insert'
                 autocmd TextChangedI * call ale#Queue(g:ale_lint_delay)
             endif
         endif