diff --git a/composer.json b/composer.json
index 3022dbc50..06fd8e13d 100644
--- a/composer.json
+++ b/composer.json
@@ -16,7 +16,7 @@
         "openlss/lib-array2xml": "^0.0.10||^0.5.1",
         "muglug/package-versions-56": "1.2.3"
     },
-    "bin": ["psalm"],
+    "bin": ["psalm", "psalter"],
     "autoload": {
         "psr-4": {
             "Psalm\\": "src/Psalm"
diff --git a/psalter b/psalter
new file mode 100755
index 000000000..da332d144
--- /dev/null
+++ b/psalter
@@ -0,0 +1,2 @@
+#!/usr/bin/env php
+<?php require_once __DIR__ . DIRECTORY_SEPARATOR . 'src' . DIRECTORY_SEPARATOR . 'psalter.php';
diff --git a/src/Psalm/Checker/CommentChecker.php b/src/Psalm/Checker/CommentChecker.php
index c95cea3af..020315acf 100644
--- a/src/Psalm/Checker/CommentChecker.php
+++ b/src/Psalm/Checker/CommentChecker.php
@@ -552,19 +552,15 @@ class CommentChecker
         }
 
         if ($parsed_doc_comment['specials']) {
-            $special_type_lengths = array_map('strlen', array_keys($parsed_doc_comment['specials']));
-            /** @var int */
-            $special_type_width = max($special_type_lengths) + 1;
-
             $last_type = null;
 
             foreach ($parsed_doc_comment['specials'] as $type => $lines) {
-                if ($last_type !== null && ($last_type !== 'return' || $type !== 'psalm-return')) {
+                if ($last_type !== null && ($last_type !== 'return' || $last_type !== 'psalm-return')) {
                     $doc_comment_text .= $left_padding . ' *' . PHP_EOL;
                 }
 
                 foreach ($lines as $line) {
-                    $doc_comment_text .= $left_padding . ' * @' . str_pad($type, $special_type_width) . $line . PHP_EOL;
+                    $doc_comment_text .= $left_padding . ' * @' . $type . ' ' . $line . PHP_EOL;
                 }
 
                 $last_type = $type;
diff --git a/src/Psalm/Checker/FunctionLikeChecker.php b/src/Psalm/Checker/FunctionLikeChecker.php
index 2793c89cc..7827e7140 100644
--- a/src/Psalm/Checker/FunctionLikeChecker.php
+++ b/src/Psalm/Checker/FunctionLikeChecker.php
@@ -309,8 +309,7 @@ abstract class FunctionLikeChecker extends SourceChecker implements StatementsSo
                         new MismatchingDocblockParamType(
                             'Parameter $' . $function_param->name . ' has wrong type \'' . $param_type .
                                 '\', should be \'' . $signature_type . '\'',
-                            $function_param->type_location,
-                            (string)$signature_type
+                            $function_param->type_location
                         ),
                         $storage->suppressed_issues
                     )) {
@@ -413,12 +412,19 @@ abstract class FunctionLikeChecker extends SourceChecker implements StatementsSo
                 $fleshed_out_signature_type
             )
             ) {
+                if ($project_checker->alter_code
+                    && isset($project_checker->getIssuesToFix()['MismatchingDocblockReturnType'])
+                ) {
+                    $this->addOrUpdateReturnType($project_checker, $storage->signature_return_type, true);
+
+                    return null;
+                }
+
                 if (IssueBuffer::accepts(
                     new MismatchingDocblockReturnType(
                         'Docblock has incorrect return type \'' . $storage->return_type .
                             '\', should be \'' . $storage->signature_return_type . '\'',
-                        $storage->return_type_location,
-                        (string) $storage->signature_return_type
+                        $storage->return_type_location
                     ),
                     $storage->suppressed_issues
                 )) {
@@ -1164,35 +1170,6 @@ abstract class FunctionLikeChecker extends SourceChecker implements StatementsSo
             )
         );
 
-        if (!$return_type && !$project_checker->add_docblocks && !$is_to_string) {
-            if ($this->function instanceof Closure) {
-                if (IssueBuffer::accepts(
-                    new MissingClosureReturnType(
-                        'Closure does not have a return type, expecting ' . $inferred_return_type,
-                        new CodeLocation($this, $this->function, null, true)
-                    ),
-                    $this->suppressed_issues
-                )) {
-                    // fall through
-                }
-
-                return null;
-            }
-
-            if (IssueBuffer::accepts(
-                new MissingReturnType(
-                    'Method ' . $cased_method_id . ' does not have a return type' .
-                      (!$inferred_return_type->isMixed() ? ', expecting ' . $inferred_return_type : ''),
-                    new CodeLocation($this, $this->function, null, true)
-                ),
-                $this->suppressed_issues
-            )) {
-                // fall through
-            }
-
-            return null;
-        }
-
         if ($is_to_string) {
             if (!$inferred_return_type->isMixed() && (string)$inferred_return_type !== 'string') {
                 if (IssueBuffer::accepts(
@@ -1210,9 +1187,53 @@ abstract class FunctionLikeChecker extends SourceChecker implements StatementsSo
         }
 
         if (!$return_type) {
-            if (!$inferred_return_type->isMixed()) {
-                // $project_checker->add_docblocks is always true here
-                $this->addDocblockReturnType($project_checker, $inferred_return_type);
+            if ($this->function instanceof Closure) {
+                if ($project_checker->alter_code
+                    && isset($project_checker->getIssuesToFix()['MissingClosureReturnType'])
+                ) {
+                    if ($inferred_return_type->isMixed()) {
+                        return null;
+                    }
+
+                    $this->addOrUpdateReturnType($project_checker, $inferred_return_type);
+
+                    return null;
+                }
+
+                if (IssueBuffer::accepts(
+                    new MissingClosureReturnType(
+                        'Closure does not have a return type, expecting ' . $inferred_return_type,
+                        new CodeLocation($this, $this->function, null, true)
+                    ),
+                    $this->suppressed_issues
+                )) {
+                    // fall through
+                }
+
+                return null;
+            }
+
+            if ($project_checker->alter_code
+                && isset($project_checker->getIssuesToFix()['MissingReturnType'])
+            ) {
+                if ($inferred_return_type->isMixed()) {
+                    return null;
+                }
+
+                $this->addOrUpdateReturnType($project_checker, $inferred_return_type);
+
+                return null;
+            }
+
+            if (IssueBuffer::accepts(
+                new MissingReturnType(
+                    'Method ' . $cased_method_id . ' does not have a return type' .
+                      (!$inferred_return_type->isMixed() ? ', expecting ' . $inferred_return_type : ''),
+                    new CodeLocation($this, $this->function, null, true)
+                ),
+                $this->suppressed_issues
+            )) {
+                // fall through
             }
 
             return null;
@@ -1237,6 +1258,12 @@ abstract class FunctionLikeChecker extends SourceChecker implements StatementsSo
                 return null;
             }
 
+            if ($project_checker->alter_code && isset(getIssuesToFix()['InvalidReturnType'])) {
+                $this->addOrUpdateReturnType($project_checker, Type::getVoid());
+
+                return null;
+            }
+
             if (IssueBuffer::accepts(
                 new InvalidReturnType(
                     'No return statements were found for method ' . $cased_method_id .
@@ -1285,12 +1312,19 @@ abstract class FunctionLikeChecker extends SourceChecker implements StatementsSo
                 && !$declared_return_type->isNullable()
                 && !$declared_return_type->isVoid()
             ) {
+                if ($project_checker->alter_code
+                    && isset($project_checker->getIssuesToFix()['NullableInferredReturnType'])
+                ) {
+                    $this->addOrUpdateReturnType($project_checker, $inferred_return_type);
+
+                    return null;
+                }
+
                 if (IssueBuffer::accepts(
                     new NullableInferredReturnType(
                         'The declared return type \'' . $declared_return_type . '\' for ' . $cased_method_id .
                             ' is not nullable, but \'' . $inferred_return_type . '\' contains null',
-                        $return_type_location,
-                        (string) $inferred_return_type
+                        $return_type_location
                     ),
                     $this->suppressed_issues
                 )) {
@@ -1302,12 +1336,19 @@ abstract class FunctionLikeChecker extends SourceChecker implements StatementsSo
                 && !$declared_return_type->isFalsable()
                 && !$declared_return_type->hasBool()
             ) {
+                if ($project_checker->alter_code
+                    && isset($project_checker->getIssuesToFix()['FalsableInferredReturnType'])
+                ) {
+                    $this->addOrUpdateReturnType($project_checker, $inferred_return_type);
+
+                    return null;
+                }
+
                 if (IssueBuffer::accepts(
                     new FalsableInferredReturnType(
                         'The declared return type \'' . $declared_return_type . '\' for ' . $cased_method_id .
                             ' does not allow false, but \'' . $inferred_return_type . '\' contains false',
-                        $return_type_location,
-                        (string) $inferred_return_type
+                        $return_type_location
                     ),
                     $this->suppressed_issues
                 )) {
@@ -1338,12 +1379,19 @@ abstract class FunctionLikeChecker extends SourceChecker implements StatementsSo
                         return false;
                     }
                 } else {
+                    if ($project_checker->alter_code
+                        && isset($project_checker->getIssuesToFix()['InvalidReturnType'])
+                    ) {
+                        $this->addOrUpdateReturnType($project_checker, $inferred_return_type);
+
+                        return null;
+                    }
+
                     if (IssueBuffer::accepts(
                         new InvalidReturnType(
                             'The declared return type \'' . $declared_return_type . '\' for ' . $cased_method_id .
                                 ' is incorrect, got \'' . $inferred_return_type . '\'',
-                            $return_type_location,
-                            (string) $inferred_return_type
+                            $return_type_location
                         ),
                         $this->suppressed_issues
                     )) {
@@ -1351,6 +1399,14 @@ abstract class FunctionLikeChecker extends SourceChecker implements StatementsSo
                     }
                 }
             } elseif (!$inferred_return_type->isNullable() && $declared_return_type->isNullable()) {
+                if ($project_checker->alter_code
+                    && isset($project_checker->getIssuesToFix()['LessSpecificReturnType'])
+                ) {
+                    $this->addOrUpdateReturnType($project_checker, $inferred_return_type);
+
+                    return null;
+                }
+
                 if (IssueBuffer::accepts(
                     new LessSpecificReturnType(
                         'The inferred return type \'' . $inferred_return_type . '\' for ' . $cased_method_id .
@@ -1368,20 +1424,29 @@ abstract class FunctionLikeChecker extends SourceChecker implements StatementsSo
     }
 
     /**
-     * @param Type\Union $inferred_return_type
+     * @param bool $docblock_only
      *
      * @return void
      */
-    private function addDocblockReturnType(ProjectChecker $project_checker, Type\Union $inferred_return_type)
-    {
+    private function addOrUpdateReturnType(
+        ProjectChecker $project_checker,
+        Type\Union $inferred_return_type,
+        $docblock_only = false
+    ) {
         $manipulator = FunctionDocblockManipulator::getForFunction(
             $project_checker,
             $this->source->getFilePath(),
             $this->getMethodId(),
             $this->function
         );
-
-        $manipulator->setDocblockReturnType(
+        $manipulator->setReturnType(
+            !$docblock_only && $project_checker->php_major_version >= 7
+                ? $inferred_return_type->toPhpString(
+                    $this->source->getAliasedClassesFlipped(),
+                    $this->source->getFQCLN(),
+                    $project_checker->php_major_version,
+                    $project_checker->php_minor_version
+                ) : null,
             $inferred_return_type->toNamespacedString(
                 $this->source->getAliasedClassesFlipped(),
                 $this->source->getFQCLN(),
@@ -1391,7 +1456,8 @@ abstract class FunctionLikeChecker extends SourceChecker implements StatementsSo
                 $this->source->getAliasedClassesFlipped(),
                 $this->source->getFQCLN(),
                 true
-            )
+            ),
+            $inferred_return_type->canBeFullyExpressedInPhp()
         );
     }
 
diff --git a/src/Psalm/Checker/ProjectChecker.php b/src/Psalm/Checker/ProjectChecker.php
index 720b41dc6..0967110d6 100644
--- a/src/Psalm/Checker/ProjectChecker.php
+++ b/src/Psalm/Checker/ProjectChecker.php
@@ -87,7 +87,7 @@ class ProjectChecker
     /**
      * @var bool
      */
-    public $add_docblocks = false;
+    public $alter_code = false;
 
     /**
      * @var bool
@@ -259,6 +259,16 @@ class ProjectChecker
      */
     private $issues_to_fix = [];
 
+    /**
+     * @var int
+     */
+    public $php_major_version = PHP_MAJOR_VERSION;
+
+    /**
+     * @var int
+     */
+    public $php_minor_version = PHP_MINOR_VERSION;
+
     const TYPE_CONSOLE = 'console';
     const TYPE_JSON = 'json';
     const TYPE_EMACS = 'emacs';
@@ -1004,7 +1014,7 @@ class ProjectChecker
             }
         }
 
-        if ($this->replace_code || $this->add_docblocks || $this->issues_to_fix) {
+        if ($this->replace_code || $this->alter_code || $this->issues_to_fix) {
             foreach ($this->files_to_report as $file_path) {
                 $this->updateFile($file_path, true);
             }
@@ -1019,7 +1029,7 @@ class ProjectChecker
      */
     public function updateFile($file_path, $output_changes = false)
     {
-        if ($this->add_docblocks) {
+        if ($this->alter_code) {
             $new_return_type_manipulations = FunctionDocblockManipulator::getManipulationsForFile($file_path);
         } else {
             $new_return_type_manipulations = [];
@@ -2082,19 +2092,16 @@ class ProjectChecker
     }
 
     /**
+     * @param int $php_major_version
+     * @param int $php_minor_version
+     *
      * @return void
      */
-    public function addDocblocksAfterCompletion()
+    public function alterCodeAfterCompletion($php_major_version, $php_minor_version)
     {
-        $this->add_docblocks = true;
-    }
-
-    /**
-     * @return void
-     */
-    public function replaceCodeAfterCompletion()
-    {
-        $this->replace_code = true;
+        $this->alter_code = true;
+        $this->php_major_version = $php_major_version;
+        $this->php_minor_version = $php_minor_version;
     }
 
     /**
@@ -2102,13 +2109,15 @@ class ProjectChecker
      *
      * @return void
      */
-    public function fixIssuesAfterCompletion(array $issues)
+    public function setIssuesToFix(array $issues)
     {
         $this->issues_to_fix = $issues;
     }
 
     /**
      * @return array<string, bool>
+     *
+     * @psalm-suppress PossiblyUnusedMethod - need to fix #422
      */
     public function getIssuesToFix()
     {
diff --git a/src/Psalm/Checker/StatementsChecker.php b/src/Psalm/Checker/StatementsChecker.php
index a1dde0c7e..a46777d28 100644
--- a/src/Psalm/Checker/StatementsChecker.php
+++ b/src/Psalm/Checker/StatementsChecker.php
@@ -1023,7 +1023,6 @@ class StatementsChecker extends SourceChecker implements StatementsSource
 
                 if ($storage->return_type
                     && !$storage->return_type->isMixed()
-                    && !$project_checker->add_docblocks
                 ) {
                     $inferred_type = ExpressionChecker::fleshOutType(
                         $project_checker,
diff --git a/src/Psalm/FileManipulation/FunctionDocblockManipulator.php b/src/Psalm/FileManipulation/FunctionDocblockManipulator.php
index 8b0460b8e..2bc394bea 100644
--- a/src/Psalm/FileManipulation/FunctionDocblockManipulator.php
+++ b/src/Psalm/FileManipulation/FunctionDocblockManipulator.php
@@ -2,6 +2,7 @@
 namespace Psalm\FileManipulation;
 
 use PhpParser\Node\Expr\Closure;
+use PhpParser\Node\FunctionLike;
 use PhpParser\Node\Stmt\ClassMethod;
 use PhpParser\Node\Stmt\Function_;
 use Psalm\Checker\CommentChecker;
@@ -28,6 +29,21 @@ class FunctionDocblockManipulator
     /** @var int */
     private $docblock_end;
 
+    /** @var int */
+    private $return_typehint_area_start;
+
+    /** @var ?int */
+    private $return_typehint_start;
+
+    /** @var ?int */
+    private $return_typehint_end;
+
+    /** @var ?string */
+    private $new_php_return_type;
+
+    /** @var bool */
+    private $return_type_is_php_compatible = false;
+
     /** @var ?string */
     private $new_phpdoc_return_type;
 
@@ -44,8 +60,12 @@ class FunctionDocblockManipulator
      *
      * @return self
      */
-    public static function getForFunction(ProjectChecker $project_checker, $file_path, $function_id, $stmt)
-    {
+    public static function getForFunction(
+        ProjectChecker $project_checker,
+        $file_path,
+        $function_id,
+        FunctionLike $stmt
+    ) {
         if (isset(self::$manipulators[$file_path][$function_id])) {
             return self::$manipulators[$file_path][$function_id];
         }
@@ -62,32 +82,99 @@ class FunctionDocblockManipulator
      * @param string $file_path
      * @param Closure|Function_|ClassMethod $stmt
      */
-    private function __construct($file_path, $stmt, ProjectChecker $project_checker)
+    private function __construct($file_path, FunctionLike $stmt, ProjectChecker $project_checker)
     {
         $this->stmt = $stmt;
         $docblock = $stmt->getDocComment();
         $this->docblock_start = $docblock ? $docblock->getFilePos() : (int)$stmt->getAttribute('startFilePos');
-        $this->docblock_end = (int)$stmt->getAttribute('startFilePos');
+        $this->docblock_end = $function_start = (int)$stmt->getAttribute('startFilePos');
+        $function_end = (int)$stmt->getAttribute('endFilePos');
+
+        $file_contents = $project_checker->getFileContents($file_path);
+
+        $last_arg_position = $stmt->params
+            ? (int) $stmt->params[count($stmt->params) - 1]->getAttribute('endFilePos')
+            : null;
+
+        if ($stmt instanceof Closure && $stmt->uses) {
+            $last_arg_position = (int) $stmt->uses[count($stmt->uses) - 1]->getAttribute('endFilePos');
+        }
+
+        $end_bracket_position = (int) strpos($file_contents, ')', $last_arg_position ?: $function_start);
+
+        $this->return_typehint_area_start = $end_bracket_position + 1;
+
+        $function_code = substr($file_contents, $function_start, $function_end);
+
+        $function_code_after_bracket = substr($function_code, $end_bracket_position + 1 - $function_start);
+
+        // do a little parsing here
+        /** @var array<int, string> */
+        $chars = str_split($function_code_after_bracket);
+
+        foreach ($chars as $i => $char) {
+            switch ($char) {
+                case PHP_EOL:
+                    continue;
+
+                case ':':
+                    continue;
+
+                case '/':
+                    // @todo handle comments in this area
+                    throw new \UnexpectedValueException('Not expecting comments where return types should live');
+
+                case '{':
+                    break 2;
+
+                case '?':
+                    $this->return_typehint_start = $i + $end_bracket_position + 1;
+                    break;
+            }
+
+            if (preg_match('/\w/', $char)) {
+                if ($this->return_typehint_start === null) {
+                    $this->return_typehint_start = $i + $end_bracket_position + 1;
+                }
+
+                if (!preg_match('/\w/', $chars[$i + 1])) {
+                    $this->return_typehint_end = $i + $end_bracket_position + 2;
+                    break;
+                }
+            }
+        }
+
+        $preceding_newline_pos = strrpos($file_contents, PHP_EOL, $this->docblock_end - strlen($file_contents));
+
+        if ($preceding_newline_pos === false) {
+            $this->indentation = '';
+
+            return;
+        }
+
+        $first_line = substr($file_contents, $preceding_newline_pos + 1, $this->docblock_end - $preceding_newline_pos);
 
-        $file_lines = explode(PHP_EOL, $project_checker->getFileContents($file_path));
-        $first_line = $file_lines[$stmt->getLine() - 1];
         $this->indentation = str_replace(ltrim($first_line), '', $first_line);
     }
 
     /**
      * Sets the new docblock return type
      *
+     * @param   ?string     $php_type
      * @param   string      $new_type
      * @param   string      $phpdoc_type
+     * @param   bool        $is_php_compatible
      *
      * @return  void
      */
-    public function setDocblockReturnType($new_type, $phpdoc_type)
+    public function setReturnType($php_type, $new_type, $phpdoc_type, $is_php_compatible)
     {
         $new_type = str_replace(['<mixed, mixed>', '<empty, empty>'], '', $new_type);
 
+        $this->new_php_return_type = $php_type;
         $this->new_phpdoc_return_type = $phpdoc_type;
         $this->new_psalm_return_type = $new_type;
+        $this->return_type_is_php_compatible = $is_php_compatible;
     }
 
     /**
@@ -131,11 +218,32 @@ class FunctionDocblockManipulator
         $file_manipulations = [];
 
         foreach (self::$ordered_manipulators[$file_path] as $manipulator) {
-            $file_manipulations[$manipulator->docblock_start] = new FileManipulation(
-                $manipulator->docblock_start,
-                $manipulator->docblock_end,
-                $manipulator->getDocblock()
-            );
+            if ($manipulator->new_php_return_type) {
+                if ($manipulator->return_typehint_start && $manipulator->return_typehint_end) {
+                    $file_manipulations[$manipulator->return_typehint_start] = new FileManipulation(
+                        $manipulator->return_typehint_start,
+                        $manipulator->return_typehint_end,
+                        $manipulator->new_php_return_type
+                    );
+                } else {
+                    $file_manipulations[$manipulator->return_typehint_area_start] = new FileManipulation(
+                        $manipulator->return_typehint_area_start,
+                        $manipulator->return_typehint_area_start,
+                        ' : ' . $manipulator->new_php_return_type
+                    );
+                }
+            }
+
+            if (!$manipulator->new_php_return_type
+                || !$manipulator->return_type_is_php_compatible
+                || $manipulator->docblock_start !== $manipulator->docblock_end
+            ) {
+                $file_manipulations[$manipulator->docblock_start] = new FileManipulation(
+                    $manipulator->docblock_start,
+                    $manipulator->docblock_end,
+                    $manipulator->getDocblock()
+                );
+            }
         }
 
         return $file_manipulations;
diff --git a/src/Psalm/Issue/FixableCodeIssue.php b/src/Psalm/Issue/FixableCodeIssue.php
index 812397a3c..b67acff64 100644
--- a/src/Psalm/Issue/FixableCodeIssue.php
+++ b/src/Psalm/Issue/FixableCodeIssue.php
@@ -1,34 +1,6 @@
 <?php
 namespace Psalm\Issue;
 
-use Psalm\CodeLocation;
-
 abstract class FixableCodeIssue extends CodeIssue
 {
-    /**
-     * @var ?string
-     */
-    protected $replacement_text;
-
-    /**
-     * @param string        $message
-     * @param CodeLocation  $code_location
-     * @param string|null   $replacement_text
-     */
-    public function __construct(
-        $message,
-        CodeLocation $code_location,
-        $replacement_text = null
-    ) {
-        parent::__construct($message, $code_location);
-        $this->replacement_text = $replacement_text;
-    }
-
-    /**
-     * @return ?string
-     */
-    public function getReplacementText()
-    {
-        return $this->replacement_text;
-    }
 }
diff --git a/src/Psalm/IssueBuffer.php b/src/Psalm/IssueBuffer.php
index ad4995e10..bd3238586 100644
--- a/src/Psalm/IssueBuffer.php
+++ b/src/Psalm/IssueBuffer.php
@@ -3,8 +3,6 @@ namespace Psalm;
 
 use LSS\Array2XML;
 use Psalm\Checker\ProjectChecker;
-use Psalm\FileManipulation\FileManipulation;
-use Psalm\FileManipulation\FileManipulationBuffer;
 use Psalm\Issue\CodeIssue;
 
 class IssueBuffer
@@ -81,24 +79,13 @@ class IssueBuffer
     public static function add(CodeIssue $e)
     {
         $config = Config::getInstance();
-        $project_checker = ProjectChecker::getInstance();
 
         $fqcn_parts = explode('\\', get_class($e));
         $issue_type = array_pop($fqcn_parts);
 
-        $issues_to_fix = \Psalm\Checker\ProjectChecker::getInstance()->getIssuesToFix();
-
-        if (isset($issues_to_fix[$issue_type])
-            && $e instanceof \Psalm\Issue\FixableCodeIssue
-            && $replacement_text = $e->getReplacementText()
-        ) {
-            $code_location = $e->getLocation();
-            $bounds = $code_location->getSelectionBounds();
-            FileManipulationBuffer::add(
-                $e->getFilePath(),
-                [new FileManipulation($bounds[0], $bounds[1], $replacement_text)]
-            );
+        $project_checker = ProjectChecker::getInstance();
 
+        if ($project_checker->alter_code) {
             return false;
         }
 
diff --git a/src/Psalm/Type/Atomic.php b/src/Psalm/Type/Atomic.php
index 324bae6f5..9f1cd2a41 100644
--- a/src/Psalm/Type/Atomic.php
+++ b/src/Psalm/Type/Atomic.php
@@ -251,6 +251,21 @@ abstract class Atomic
         return $this->getKey();
     }
 
+    /**
+     * @param  array<string> $aliased_classes
+     * @param  string|null   $this_class
+     * @param  int           $php_major_version
+     * @param  int           $php_minor_version
+     *
+     * @return ?string
+     */
+    abstract public function toPhpString(array $aliased_classes, $this_class, $php_major_version, $php_minor_version);
+
+    /**
+     * @return bool
+     */
+    abstract public function canBeFullyExpressedInPhp();
+
     /**
      * @return void
      */
diff --git a/src/Psalm/Type/Atomic/ObjectLike.php b/src/Psalm/Type/Atomic/ObjectLike.php
index 7a6eb38da..abed26540 100644
--- a/src/Psalm/Type/Atomic/ObjectLike.php
+++ b/src/Psalm/Type/Atomic/ObjectLike.php
@@ -80,6 +80,24 @@ class ObjectLike extends \Psalm\Type\Atomic
                 '}';
     }
 
+    /**
+     * @param  array<string> $aliased_classes
+     * @param  string|null   $this_class
+     * @param  int           $php_major_version
+     * @param  int           $php_minor_version
+     *
+     * @return string
+     */
+    public function toPhpString(array $aliased_classes, $this_class, $php_major_version, $php_minor_version)
+    {
+        return $this->getKey();
+    }
+
+    public function canBeFullyExpressedInPhp()
+    {
+        return false;
+    }
+
     /**
      * @return Union
      */
diff --git a/src/Psalm/Type/Atomic/Scalar.php b/src/Psalm/Type/Atomic/Scalar.php
index 9ddc67b64..a65a103d6 100644
--- a/src/Psalm/Type/Atomic/Scalar.php
+++ b/src/Psalm/Type/Atomic/Scalar.php
@@ -3,4 +3,24 @@ namespace Psalm\Type\Atomic;
 
 abstract class Scalar extends \Psalm\Type\Atomic
 {
+    /**
+     * @param  array<string> $aliased_classes
+     * @param  string|null   $this_class
+     * @param  int           $php_major_version
+     * @param  int           $php_minor_version
+     *
+     * @return ?string
+     */
+    public function toPhpString(array $aliased_classes, $this_class, $php_major_version, $php_minor_version)
+    {
+        return $php_major_version >= 7 ? $this->getKey() : null;
+    }
+
+    /**
+     * @return bool
+     */
+    public function canBeFullyExpressedInPhp()
+    {
+        return true;
+    }
 }
diff --git a/src/Psalm/Type/Atomic/T.php b/src/Psalm/Type/Atomic/T.php
index db4acb380..b56fea7fa 100644
--- a/src/Psalm/Type/Atomic/T.php
+++ b/src/Psalm/Type/Atomic/T.php
@@ -17,4 +17,12 @@ abstract class T extends TString
     {
         $this->typeof = $typeof;
     }
+
+    /**
+     * @return bool
+     */
+    public function canBeFullyExpressedInPhp()
+    {
+        return false;
+    }
 }
diff --git a/src/Psalm/Type/Atomic/TArray.php b/src/Psalm/Type/Atomic/TArray.php
index 1e3cce967..c7298e1d1 100644
--- a/src/Psalm/Type/Atomic/TArray.php
+++ b/src/Psalm/Type/Atomic/TArray.php
@@ -27,4 +27,22 @@ class TArray extends \Psalm\Type\Atomic implements Generic
     {
         return 'array';
     }
+
+    /**
+     * @param  array<string> $aliased_classes
+     * @param  string|null   $this_class
+     * @param  int           $php_major_version
+     * @param  int           $php_minor_version
+     *
+     * @return string
+     */
+    public function toPhpString(array $aliased_classes, $this_class, $php_major_version, $php_minor_version)
+    {
+        return $this->getKey();
+    }
+
+    public function canBeFullyExpressedInPhp()
+    {
+        return $this->type_params[0]->isMixed() && $this->type_params[1]->isMixed();
+    }
 }
diff --git a/src/Psalm/Type/Atomic/TBool.php b/src/Psalm/Type/Atomic/TBool.php
index f54da514b..e8d2950c2 100644
--- a/src/Psalm/Type/Atomic/TBool.php
+++ b/src/Psalm/Type/Atomic/TBool.php
@@ -15,4 +15,17 @@ class TBool extends Scalar
     {
         return 'bool';
     }
+
+    /**
+     * @param  array<string> $aliased_classes
+     * @param  string|null   $this_class
+     * @param  int           $php_major_version
+     * @param  int           $php_minor_version
+     *
+     * @return ?string
+     */
+    public function toPhpString(array $aliased_classes, $this_class, $php_major_version, $php_minor_version)
+    {
+        return $php_major_version >= 7 ? 'bool' : null;
+    }
 }
diff --git a/src/Psalm/Type/Atomic/TCallable.php b/src/Psalm/Type/Atomic/TCallable.php
index cba0a3fef..96d7528f8 100644
--- a/src/Psalm/Type/Atomic/TCallable.php
+++ b/src/Psalm/Type/Atomic/TCallable.php
@@ -15,4 +15,22 @@ class TCallable extends \Psalm\Type\Atomic
     {
         return 'callable';
     }
+
+    /**
+     * @param  array<string> $aliased_classes
+     * @param  string|null   $this_class
+     * @param  int           $php_major_version
+     * @param  int           $php_minor_version
+     *
+     * @return ?string
+     */
+    public function toPhpString(array $aliased_classes, $this_class, $php_major_version, $php_minor_version)
+    {
+        return null;
+    }
+
+    public function canBeFullyExpressedInPhp()
+    {
+        return false;
+    }
 }
diff --git a/src/Psalm/Type/Atomic/TEmpty.php b/src/Psalm/Type/Atomic/TEmpty.php
index 301556af5..6cd296bf7 100644
--- a/src/Psalm/Type/Atomic/TEmpty.php
+++ b/src/Psalm/Type/Atomic/TEmpty.php
@@ -15,4 +15,17 @@ class TEmpty extends Scalar
     {
         return 'empty';
     }
+
+    /**
+     * @param  array<string> $aliased_classes
+     * @param  string|null   $this_class
+     * @param  int           $php_major_version
+     * @param  int           $php_minor_version
+     *
+     * @return ?string
+     */
+    public function toPhpString(array $aliased_classes, $this_class, $php_major_version, $php_minor_version)
+    {
+        return null;
+    }
 }
diff --git a/src/Psalm/Type/Atomic/TFalse.php b/src/Psalm/Type/Atomic/TFalse.php
index 39c9b110c..181e2f214 100644
--- a/src/Psalm/Type/Atomic/TFalse.php
+++ b/src/Psalm/Type/Atomic/TFalse.php
@@ -15,4 +15,9 @@ class TFalse extends TBool
     {
         return 'false';
     }
+
+    public function canBeFullyExpressedInPhp()
+    {
+        return false;
+    }
 }
diff --git a/src/Psalm/Type/Atomic/TGenericObject.php b/src/Psalm/Type/Atomic/TGenericObject.php
index 134396429..67dab2fa5 100644
--- a/src/Psalm/Type/Atomic/TGenericObject.php
+++ b/src/Psalm/Type/Atomic/TGenericObject.php
@@ -17,4 +17,12 @@ class TGenericObject extends TNamedObject implements Generic
         $this->value = $value;
         $this->type_params = $type_params;
     }
+
+    /**
+     * @return bool
+     */
+    public function canBeFullyExpressedInPhp()
+    {
+        return false;
+    }
 }
diff --git a/src/Psalm/Type/Atomic/TMixed.php b/src/Psalm/Type/Atomic/TMixed.php
index b760cfa85..3089980d8 100644
--- a/src/Psalm/Type/Atomic/TMixed.php
+++ b/src/Psalm/Type/Atomic/TMixed.php
@@ -15,4 +15,22 @@ class TMixed extends \Psalm\Type\Atomic
     {
         return 'mixed';
     }
+
+    /**
+     * @param  array<string> $aliased_classes
+     * @param  string|null   $this_class
+     * @param  int           $php_major_version
+     * @param  int           $php_minor_version
+     *
+     * @return ?string
+     */
+    public function toPhpString(array $aliased_classes, $this_class, $php_major_version, $php_minor_version)
+    {
+        return null;
+    }
+
+    public function canBeFullyExpressedInPhp()
+    {
+        return false;
+    }
 }
diff --git a/src/Psalm/Type/Atomic/TNamedObject.php b/src/Psalm/Type/Atomic/TNamedObject.php
index 0f73f1a2f..c2cb0a70f 100644
--- a/src/Psalm/Type/Atomic/TNamedObject.php
+++ b/src/Psalm/Type/Atomic/TNamedObject.php
@@ -67,6 +67,24 @@ class TNamedObject extends Atomic
         return '\\' . $this->value;
     }
 
+    /**
+     * @param  array<string> $aliased_classes
+     * @param  string|null   $this_class
+     * @param  int           $php_major_version
+     * @param  int           $php_minor_version
+     *
+     * @return string
+     */
+    public function toPhpString(array $aliased_classes, $this_class, $php_major_version, $php_minor_version)
+    {
+        return $this->toNamespacedString($aliased_classes, $this_class, false);
+    }
+
+    public function canBeFullyExpressedInPhp()
+    {
+        return true;
+    }
+
     /**
      * @param TNamedObject $type
      *
diff --git a/src/Psalm/Type/Atomic/TNull.php b/src/Psalm/Type/Atomic/TNull.php
index 6d3178a0a..66e0b2443 100644
--- a/src/Psalm/Type/Atomic/TNull.php
+++ b/src/Psalm/Type/Atomic/TNull.php
@@ -15,4 +15,22 @@ class TNull extends \Psalm\Type\Atomic
     {
         return 'null';
     }
+
+    /**
+     * @param  array<string> $aliased_classes
+     * @param  string|null   $this_class
+     * @param  int           $php_major_version
+     * @param  int           $php_minor_version
+     *
+     * @return ?string
+     */
+    public function toPhpString(array $aliased_classes, $this_class, $php_major_version, $php_minor_version)
+    {
+        return null;
+    }
+
+    public function canBeFullyExpressedInPhp()
+    {
+        return false;
+    }
 }
diff --git a/src/Psalm/Type/Atomic/TNumeric.php b/src/Psalm/Type/Atomic/TNumeric.php
index 2d9cdbcbd..23c872ef3 100644
--- a/src/Psalm/Type/Atomic/TNumeric.php
+++ b/src/Psalm/Type/Atomic/TNumeric.php
@@ -15,4 +15,17 @@ class TNumeric extends Scalar
     {
         return 'numeric';
     }
+
+    /**
+     * @param  array<string> $aliased_classes
+     * @param  string|null   $this_class
+     * @param  int           $php_major_version
+     * @param  int           $php_minor_version
+     *
+     * @return ?string
+     */
+    public function toPhpString(array $aliased_classes, $this_class, $php_major_version, $php_minor_version)
+    {
+        return null;
+    }
 }
diff --git a/src/Psalm/Type/Atomic/TNumericString.php b/src/Psalm/Type/Atomic/TNumericString.php
index 87811ed9a..c00032298 100644
--- a/src/Psalm/Type/Atomic/TNumericString.php
+++ b/src/Psalm/Type/Atomic/TNumericString.php
@@ -15,4 +15,12 @@ class TNumericString extends TString
     {
         return $this->getKey();
     }
+
+    /**
+     * @return bool
+     */
+    public function canBeFullyExpressedInPhp()
+    {
+        return false;
+    }
 }
diff --git a/src/Psalm/Type/Atomic/TObject.php b/src/Psalm/Type/Atomic/TObject.php
index c04f0c995..18f4b44dc 100644
--- a/src/Psalm/Type/Atomic/TObject.php
+++ b/src/Psalm/Type/Atomic/TObject.php
@@ -15,4 +15,22 @@ class TObject extends \Psalm\Type\Atomic
     {
         return 'object';
     }
+
+    /**
+     * @param  array<string> $aliased_classes
+     * @param  string|null   $this_class
+     * @param  int           $php_major_version
+     * @param  int           $php_minor_version
+     *
+     * @return ?string
+     */
+    public function toPhpString(array $aliased_classes, $this_class, $php_major_version, $php_minor_version)
+    {
+        return $php_major_version >= 7 && $php_minor_version >= 2 ? $this->getKey() : null;
+    }
+
+    public function canBeFullyExpressedInPhp()
+    {
+        return true;
+    }
 }
diff --git a/src/Psalm/Type/Atomic/TResource.php b/src/Psalm/Type/Atomic/TResource.php
index 253b08c5f..8410b75e5 100644
--- a/src/Psalm/Type/Atomic/TResource.php
+++ b/src/Psalm/Type/Atomic/TResource.php
@@ -15,4 +15,22 @@ class TResource extends \Psalm\Type\Atomic
     {
         return 'resource';
     }
+
+    /**
+     * @param  array<string> $aliased_classes
+     * @param  string|null   $this_class
+     * @param  int           $php_major_version
+     * @param  int           $php_minor_version
+     *
+     * @return ?string
+     */
+    public function toPhpString(array $aliased_classes, $this_class, $php_major_version, $php_minor_version)
+    {
+        return null;
+    }
+
+    public function canBeFullyExpressedInPhp()
+    {
+        return false;
+    }
 }
diff --git a/src/Psalm/Type/Atomic/TScalar.php b/src/Psalm/Type/Atomic/TScalar.php
index 5f5e6ced7..7297079a8 100644
--- a/src/Psalm/Type/Atomic/TScalar.php
+++ b/src/Psalm/Type/Atomic/TScalar.php
@@ -15,4 +15,22 @@ class TScalar extends Scalar
     {
         return 'scalar';
     }
+
+    /**
+     * @param  array<string> $aliased_classes
+     * @param  string|null   $this_class
+     * @param  int           $php_major_version
+     * @param  int           $php_minor_version
+     *
+     * @return ?string
+     */
+    public function toPhpString(array $aliased_classes, $this_class, $php_major_version, $php_minor_version)
+    {
+        return null;
+    }
+
+    public function canBeFullyExpressedInPhp()
+    {
+        return false;
+    }
 }
diff --git a/src/Psalm/Type/Atomic/TTrue.php b/src/Psalm/Type/Atomic/TTrue.php
index 9a4486d58..248293c01 100644
--- a/src/Psalm/Type/Atomic/TTrue.php
+++ b/src/Psalm/Type/Atomic/TTrue.php
@@ -15,4 +15,9 @@ class TTrue extends TBool
     {
         return 'true';
     }
+
+    public function canBeFullyExpressedInPhp()
+    {
+        return false;
+    }
 }
diff --git a/src/Psalm/Type/Atomic/TVoid.php b/src/Psalm/Type/Atomic/TVoid.php
index d2ab89df3..258358e22 100644
--- a/src/Psalm/Type/Atomic/TVoid.php
+++ b/src/Psalm/Type/Atomic/TVoid.php
@@ -15,4 +15,22 @@ class TVoid extends \Psalm\Type\Atomic
     {
         return 'void';
     }
+
+    /**
+     * @param  array<string> $aliased_classes
+     * @param  string|null   $this_class
+     * @param  int           $php_major_version
+     * @param  int           $php_minor_version
+     *
+     * @return ?string
+     */
+    public function toPhpString(array $aliased_classes, $this_class, $php_major_version, $php_minor_version)
+    {
+        return $php_major_version >= 7 && $php_minor_version >= 1 ? $this->getKey() : null;
+    }
+
+    public function canBeFullyExpressedInPhp()
+    {
+        return true;
+    }
 }
diff --git a/src/Psalm/Type/Union.php b/src/Psalm/Type/Union.php
index 953f29004..2ecf9596c 100644
--- a/src/Psalm/Type/Union.php
+++ b/src/Psalm/Type/Union.php
@@ -111,6 +111,78 @@ class Union
         );
     }
 
+    /**
+     * @param  array<string> $aliased_classes
+     * @param  string|null   $this_class
+     * @param  int           $php_major_version
+     * @param  int           $php_minor_version
+     *
+     * @return ?string
+     */
+    public function toPhpString(array $aliased_classes, $this_class, $php_major_version, $php_minor_version)
+    {
+        $nullable = false;
+
+        if (count($this->types) > 2
+            || (
+                count($this->types) === 2
+                && (!isset($this->types['null'])
+                    || $php_major_version < 7
+                    || $php_minor_version < 1)
+            )
+        ) {
+            return null;
+        }
+
+        $types = $this->types;
+
+        if (isset($types['null'])) {
+            unset($types['null']);
+
+            $nullable = true;
+        }
+
+        $atomic_type = array_values($types)[0];
+
+        $atomic_type_string = $atomic_type->toPhpString(
+            $aliased_classes,
+            $this_class,
+            $php_major_version,
+            $php_minor_version
+        );
+
+        if ($atomic_type_string) {
+            return ($nullable ? '?' : '') . $atomic_type_string;
+        }
+
+        return null;
+    }
+
+    /**
+     * @return bool
+     */
+    public function canBeFullyExpressedInPhp()
+    {
+        if (count($this->types) > 2
+            || (
+                count($this->types) === 2
+                && !isset($this->types['null'])
+            )
+        ) {
+            return false;
+        }
+
+        $types = $this->types;
+
+        if (isset($types['null'])) {
+            unset($types['null']);
+        }
+
+        $atomic_type = array_values($types)[0];
+
+        return $atomic_type->canBeFullyExpressedInPhp();
+    }
+
     /**
      * @return void
      */
diff --git a/src/command_functions.php b/src/command_functions.php
new file mode 100644
index 000000000..95ca41ce9
--- /dev/null
+++ b/src/command_functions.php
@@ -0,0 +1,133 @@
+<?php
+
+/**
+ * @param  string $current_dir
+ *
+ * @return void
+ */
+function requireAutoloaders($current_dir)
+{
+    $autoload_roots = [$current_dir];
+
+    $psalm_dir = dirname(__DIR__);
+
+    if (realpath($psalm_dir) !== realpath($current_dir)) {
+        $autoload_roots[] = $psalm_dir;
+    }
+
+    $autoload_files = [];
+
+    foreach ($autoload_roots as $autoload_root) {
+        $has_autoloader = false;
+
+        $nested_autoload_file = dirname(dirname($autoload_root)) . DIRECTORY_SEPARATOR . 'autoload.php';
+
+        if (file_exists($nested_autoload_file)) {
+            $autoload_files[] = realpath($nested_autoload_file);
+            $has_autoloader = true;
+        }
+
+        $vendor_autoload_file = $autoload_root . DIRECTORY_SEPARATOR . 'vendor' . DIRECTORY_SEPARATOR . 'autoload.php';
+
+        if (file_exists($vendor_autoload_file)) {
+            $autoload_files[] = realpath($vendor_autoload_file);
+            $has_autoloader = true;
+        }
+
+        if (!$has_autoloader) {
+            $error_message = 'Could not find any composer autoloaders in ' . $autoload_root;
+
+            if (!isset($options['r'])) {
+                $error_message .= PHP_EOL . 'Add a --root=[your/project/directory] flag '
+                    . 'to specify a particular project to run Psalm on.';
+            }
+
+            die($error_message . PHP_EOL);
+        }
+    }
+
+    foreach ($autoload_files as $file) {
+        /** @psalm-suppress UnresolvableInclude */
+        require_once $file;
+    }
+}
+
+/**
+ * @param  string|string[]|null $f_paths
+ *
+ * @return string[]|null
+ */
+function getPathsToCheck($f_paths)
+{
+    global $argv;
+
+    $paths_to_check = [];
+
+    if ($f_paths) {
+        $input_paths = is_array($f_paths) ? $f_paths : [$f_paths];
+    } else {
+        $input_paths = $argv ? $argv : null;
+    }
+
+    if ($input_paths) {
+        $filtered_input_paths = [];
+
+        for ($i = 0; $i < count($input_paths); ++$i) {
+            /** @var string */
+            $input_path = $input_paths[$i];
+
+            if (realpath($input_path) === realpath(dirname(__DIR__) . DIRECTORY_SEPARATOR . 'psalm')
+                || realpath($input_path) === realpath(dirname(__DIR__) . DIRECTORY_SEPARATOR . 'psalter')
+            ) {
+                continue;
+            }
+
+            if ($input_path[0] === '-' && strlen($input_path) === 2) {
+                if ($input_path[1] === 'c' || $input_path[1] === 'f') {
+                    ++$i;
+                }
+                continue;
+            }
+
+            if ($input_path[0] === '-' && $input_path[2] === '=') {
+                continue;
+            }
+
+            if (substr($input_path, 0, 2) === '--' && strlen($input_path) > 2) {
+                continue;
+            }
+
+            $filtered_input_paths[] = $input_path;
+        }
+
+        stream_set_blocking(STDIN, false);
+
+        if ($filtered_input_paths === ['-'] && $stdin = fgets(STDIN)) {
+            $filtered_input_paths = preg_split('/\s+/', trim($stdin));
+        }
+
+        foreach ($filtered_input_paths as $i => $path_to_check) {
+            if ($path_to_check[0] === '-') {
+                die('Invalid usage, expecting psalm [options] [file...]' . PHP_EOL);
+            }
+
+            if (!file_exists($path_to_check)) {
+                die('Cannot locate ' . $path_to_check . PHP_EOL);
+            }
+
+            $path_to_check = realpath($path_to_check);
+
+            if (!$path_to_check) {
+                die('Error getting realpath for file' . PHP_EOL);
+            }
+
+            $paths_to_check[] = $path_to_check;
+        }
+
+        if (!$paths_to_check) {
+            $paths_to_check = null;
+        }
+    }
+
+    return $paths_to_check;
+}
diff --git a/src/psalm.php b/src/psalm.php
index 3960e1076..e28d13225 100644
--- a/src/psalm.php
+++ b/src/psalm.php
@@ -1,4 +1,5 @@
 <?php
+require_once('command_functions.php');
 
 use Psalm\Checker\ProjectChecker;
 use Psalm\Config;
@@ -14,10 +15,9 @@ $options = getopt(
     'f:mhvc:ir:',
     [
         'help', 'debug', 'config:', 'monochrome', 'show-info:', 'diff',
-        'file:', 'self-check', 'add-docblocks', 'output-format:',
-        'find-dead-code', 'init', 'find-references-to:', 'root:', 'threads:',
-        'report:', 'clear-cache', 'no-cache', 'version', 'plugin:', 'replace-code',
-        'fix-code',
+        'self-check', 'output-format:', 'report:', 'find-dead-code', 'init',
+        'find-references-to:', 'root:', 'threads:', 'clear-cache', 'no-cache',
+        'version', 'plugin:',
     ]
 );
 
@@ -82,9 +82,6 @@ Options:
     --self-check
         Psalm checks itself
 
-    --add-docblocks
-        Adds correct docblock return types to the given file(s)
-
     --output-format=console
         Changes the output format. Possible values: console, json, xml
 
@@ -111,12 +108,6 @@ Options:
     --plugin=PATH
         Executes a plugin, an alternative to using the Psalm config
 
-    --replace-code
-        Processes any plugin code replacements and updates the code accordingly
-
-    --fix-issues=IssueType1,IssueType2
-        If any issues that can be fixed automatically, Psalm will update the codebase
-
 HELP;
 
     exit;
@@ -142,49 +133,7 @@ if (isset($options['r']) && is_string($options['r'])) {
     $current_dir = $root_path . DIRECTORY_SEPARATOR;
 }
 
-$autoload_roots = [$current_dir];
-
-$psalm_dir = dirname(__DIR__);
-
-if (realpath($psalm_dir) !== realpath($current_dir)) {
-    $autoload_roots[] = $psalm_dir;
-}
-
-$autoload_files = [];
-
-foreach ($autoload_roots as $autoload_root) {
-    $has_autoloader = false;
-
-    $nested_autoload_file = dirname(dirname($autoload_root)) . DIRECTORY_SEPARATOR . 'autoload.php';
-
-    if (file_exists($nested_autoload_file)) {
-        $autoload_files[] = realpath($nested_autoload_file);
-        $has_autoloader = true;
-    }
-
-    $vendor_autoload_file = $autoload_root . DIRECTORY_SEPARATOR . 'vendor' . DIRECTORY_SEPARATOR . 'autoload.php';
-
-    if (file_exists($vendor_autoload_file)) {
-        $autoload_files[] = realpath($vendor_autoload_file);
-        $has_autoloader = true;
-    }
-
-    if (!$has_autoloader) {
-        $error_message = 'Could not find any composer autoloaders in ' . $autoload_root;
-
-        if (!isset($options['r'])) {
-            $error_message .=
-                PHP_EOL . 'Add a --root=[your/project/directory] flag to specify a particular project to run Psalm on.';
-        }
-
-        die($error_message . PHP_EOL);
-    }
-}
-
-foreach ($autoload_files as $file) {
-    /** @psalm-suppress UnresolvableInclude */
-    require_once $file;
-}
+requireAutoloaders($current_dir);
 
 if (array_key_exists('v', $options)) {
     /** @var string */
@@ -263,78 +212,11 @@ if (isset($options['i'])) {
     exit('Config file created successfully. Please re-run psalm.' . PHP_EOL);
 }
 
-// get vars from options
-$debug = array_key_exists('debug', $options);
-
-if (isset($options['f'])) {
-    $input_paths = is_array($options['f']) ? $options['f'] : [$options['f']];
-} else {
-    $input_paths = $argv ? $argv : null;
-}
-
 $output_format = isset($options['output-format']) && is_string($options['output-format'])
     ? $options['output-format']
     : ProjectChecker::TYPE_CONSOLE;
 
-$paths_to_check = null;
-
-if ($input_paths) {
-    $filtered_input_paths = [];
-
-    for ($i = 0; $i < count($input_paths); ++$i) {
-        /** @var string */
-        $input_path = $input_paths[$i];
-
-        if (realpath($input_path) === realpath(dirname(__DIR__) . DIRECTORY_SEPARATOR . 'psalm')) {
-            continue;
-        }
-
-        if ($input_path[0] === '-' && strlen($input_path) === 2) {
-            if ($input_path[1] === 'c' || $input_path[1] === 'f') {
-                ++$i;
-            }
-            continue;
-        }
-
-        if ($input_path[0] === '-' && $input_path[2] === '=') {
-            continue;
-        }
-
-        if (substr($input_path, 0, 2) === '--' && strlen($input_path) > 2) {
-            continue;
-        }
-
-        $filtered_input_paths[] = $input_path;
-    }
-
-    stream_set_blocking(STDIN, false);
-
-    if ($filtered_input_paths === ['-'] && $stdin = fgets(STDIN)) {
-        $filtered_input_paths = preg_split('/\s+/', trim($stdin));
-    }
-
-    foreach ($filtered_input_paths as $i => $path_to_check) {
-        if ($path_to_check[0] === '-') {
-            die('Invalid usage, expecting psalm [options] [file...]' . PHP_EOL);
-        }
-
-        if (!file_exists($path_to_check)) {
-            die('Cannot locate ' . $path_to_check . PHP_EOL);
-        }
-
-        $path_to_check = realpath($path_to_check);
-
-        if (!$path_to_check) {
-            die('Error getting realpath for file' . PHP_EOL);
-        }
-
-        $paths_to_check[] = $path_to_check;
-    }
-
-    if (!$paths_to_check) {
-        $paths_to_check = null;
-    }
-}
+$paths_to_check = getPathsToCheck(isset($options['f']) ? $options['f'] : null);
 
 $plugins = [];
 
@@ -353,11 +235,9 @@ if ($path_to_config === false) {
     die('Could not resolve path to config ' . (string)$options['c'] . PHP_EOL);
 }
 
-$use_color = !array_key_exists('m', $options);
-
 $show_info = isset($options['show-info'])
-            ? $options['show-info'] !== 'false' && $options['show-info'] !== '0'
-            : true;
+    ? $options['show-info'] !== 'false' && $options['show-info'] !== '0'
+    : true;
 
 $is_diff = isset($options['diff']);
 
@@ -367,8 +247,6 @@ $find_references_to = isset($options['find-references-to']) && is_string($option
     ? $options['find-references-to']
     : null;
 
-$add_docblocks = isset($options['add-docblocks']);
-
 $threads = isset($options['threads']) ? (int)$options['threads'] : 1;
 
 $cache_provider = isset($options['no-cache'])
@@ -378,11 +256,11 @@ $cache_provider = isset($options['no-cache'])
 $project_checker = new ProjectChecker(
     new Psalm\Provider\FileProvider(),
     $cache_provider,
-    $use_color,
+    !array_key_exists('m', $options),
     $show_info,
     $output_format,
     $threads,
-    $debug,
+    array_key_exists('debug', $options),
     $find_dead_code || $find_references_to !== null,
     $find_references_to,
     isset($options['report']) && is_string($options['report']) ? $options['report'] : null
@@ -417,25 +295,6 @@ foreach ($plugins as $plugin_path) {
     Config::getInstance()->addPluginPath($current_dir . DIRECTORY_SEPARATOR . $plugin_path);
 }
 
-if (isset($options['replace-code'])) {
-    $project_checker->replaceCodeAfterCompletion();
-}
-
-if (isset($options['fix-issues'])) {
-    if (!is_string($options['fix-issues']) || !$options['fix-issues']) {
-        die('Expecting a comma-separated string of issues' . PHP_EOL);
-    }
-
-    $issues = explode(',', $options['fix-issues']);
-
-    $keyed_issues = [];
-    foreach ($issues as $issue) {
-        $keyed_issues[$issue] = true;
-    }
-
-    $project_checker->fixIssuesAfterCompletion($keyed_issues);
-}
-
 /** @psalm-suppress MixedArgument */
 \Psalm\IssueBuffer::setStartTime(microtime(true));
 
diff --git a/src/psalter.php b/src/psalter.php
new file mode 100644
index 000000000..7cabcf912
--- /dev/null
+++ b/src/psalter.php
@@ -0,0 +1,165 @@
+<?php
+require_once('command_functions.php');
+
+use Psalm\Checker\ProjectChecker;
+use Psalm\Config;
+
+// show all errors
+error_reporting(-1);
+ini_set('display_errors', 1);
+ini_set('display_startup_errors', 1);
+ini_set('memory_limit', '2048M');
+
+// get options from command line
+$options = getopt(
+    'f:mhr:',
+    [
+        'help', 'debug', 'config:', 'file:', 'root:',
+        'plugin:', 'replace-code', 'issues:', 'target-php-version:', 'dry-run',
+    ]
+);
+
+if (array_key_exists('help', $options)) {
+    $options['h'] = false;
+}
+
+if (array_key_exists('monochrome', $options)) {
+    $options['m'] = false;
+}
+
+if (isset($options['config'])) {
+    $options['c'] = $options['config'];
+}
+
+if (isset($options['c']) && is_array($options['c'])) {
+    die('Too many config files provided' . PHP_EOL);
+}
+
+if (array_key_exists('h', $options)) {
+    echo <<< HELP
+Usage:
+    psalm [options] [file...]
+
+Options:
+    -h, --help
+        Display this help message
+
+    --debug
+        Debug information
+
+    -c, --config=psalm.xml
+        Path to a psalm.xml configuration file. Run psalm --init to create one.
+
+    -m, --monochrome
+        Enable monochrome output
+
+    -r, --root
+        If running Psalm globally you'll need to specify a project root. Defaults to cwd
+
+    --plugin=PATH
+        Executes a plugin, an alternative to using the Psalm config
+
+    --dry-run
+        Shows a diff of all the changes, without making them
+
+    --php-version=PHP_MAJOR_VERSION.PHP_MINOR_VERSION
+
+    --issues=IssueType1,IssueType2
+        If any issues can be fixed automatically, Psalm will update the codebase
+
+HELP;
+
+    exit;
+}
+
+if (!isset($options['issues'])) {
+    die('Please specify the issues you want to fix with --issues=IssueOne,IssueTwo' . PHP_EOL);
+}
+
+if (isset($options['root'])) {
+    $options['r'] = $options['root'];
+}
+
+$current_dir = (string)getcwd() . DIRECTORY_SEPARATOR;
+
+if (isset($options['r']) && is_string($options['r'])) {
+    $root_path = realpath($options['r']);
+
+    if (!$root_path) {
+        die('Could not locate root directory ' . $current_dir . DIRECTORY_SEPARATOR . $options['r'] . PHP_EOL);
+    }
+
+    $current_dir = $root_path . DIRECTORY_SEPARATOR;
+}
+
+requireAutoloaders($current_dir);
+
+$paths_to_check = getPathsToCheck(isset($options['f']) ? $options['f'] : null);
+
+$path_to_config = isset($options['c']) && is_string($options['c']) ? realpath($options['c']) : null;
+
+if ($path_to_config === false) {
+    /** @psalm-suppress InvalidCast */
+    die('Could not resolve path to config ' . (string)$options['c'] . PHP_EOL);
+}
+
+$project_checker = new ProjectChecker(
+    new Psalm\Provider\FileProvider(),
+    new Psalm\Provider\ParserCacheProvider(),
+    !array_key_exists('m', $options),
+    false,
+    ProjectChecker::TYPE_CONSOLE,
+    1,
+    array_key_exists('debug', $options)
+);
+
+// initialise custom config, if passed
+if ($path_to_config) {
+    $project_checker->setConfigXML($path_to_config, $current_dir);
+}
+
+$config = $project_checker->getConfig();
+
+if (!$config) {
+    $project_checker->getConfigForPath($current_dir, $current_dir);
+}
+
+if (!is_string($options['issues']) || !$options['issues']) {
+    die('Expecting a comma-separated list of issues' . PHP_EOL);
+}
+
+$issues = explode(',', $options['issues']);
+
+$keyed_issues = [];
+foreach ($issues as $issue) {
+    $keyed_issues[$issue] = true;
+}
+
+$php_major_version = PHP_MAJOR_VERSION;
+$php_minor_version = PHP_MINOR_VERSION;
+
+if (isset($options['php-version'])) {
+    if (!is_string($options['php-version']) || !preg_match('/^(5\.[456]|7\.[012])^/', $options['php-version'])) {
+        die('Expecting a version number in the format x.y' . PHP_EOL);
+    }
+
+    list($php_major_version, $php_minor_version) = explode('.', $options['php-version']);
+}
+
+$project_checker->alterCodeAfterCompletion((int) $php_major_version, (int) $php_minor_version);
+$project_checker->setIssuesToFix($keyed_issues);
+
+/** @psalm-suppress MixedArgument */
+\Psalm\IssueBuffer::setStartTime(microtime(true));
+
+if ($paths_to_check === null) {
+    $project_checker->check($current_dir);
+} elseif ($paths_to_check) {
+    foreach ($paths_to_check as $path_to_check) {
+        if (is_dir($path_to_check)) {
+            $project_checker->checkDir($path_to_check);
+        } else {
+            $project_checker->checkFile($path_to_check);
+        }
+    }
+}
diff --git a/tests/FileManipulationTest.php b/tests/FileManipulationTest.php
index eeee716f4..905c11951 100644
--- a/tests/FileManipulationTest.php
+++ b/tests/FileManipulationTest.php
@@ -30,8 +30,6 @@ class FileManipulationTest extends TestCase
         }
 
         $this->project_checker->setConfig(self::$config);
-
-        $this->project_checker->add_docblocks = true;
     }
 
     /**
@@ -39,10 +37,12 @@ class FileManipulationTest extends TestCase
      *
      * @param string $input_code
      * @param string $output_code
+     * @param string $php_version
+     * @param string[] $issues_to_fix
      *
      * @return void
      */
-    public function testValidCode($input_code, $output_code)
+    public function testValidCode($input_code, $output_code, $php_version, array $issues_to_fix)
     {
         $test_name = $this->getName();
         if (strpos($test_name, 'PHP7-') !== false) {
@@ -64,9 +64,19 @@ class FileManipulationTest extends TestCase
             $input_code
         );
 
+        list($php_major_version, $php_minor_version) = explode('.', $php_version);
+
+        $keyed_issues_to_fix = [];
+
+        foreach ($issues_to_fix as $issue) {
+            $keyed_issues_to_fix[$issue] = true;
+        }
+
         $file_checker = new FileChecker($file_path, $this->project_checker);
-        $this->project_checker->addDocblocksAfterCompletion();
-        $this->project_checker->fixIssuesAfterCompletion(['InvalidReturnType' => true]);
+
+        $this->project_checker->setIssuesToFix($keyed_issues_to_fix);
+        $this->project_checker->alterCodeAfterCompletion((int) $php_major_version, (int) $php_minor_version);
+
         $file_checker->visitAndAnalyzeMethods($context);
         $this->project_checker->updateFile($file_path);
         $this->assertSame($output_code, $this->project_checker->getFileContents($file_path));
@@ -78,7 +88,7 @@ class FileManipulationTest extends TestCase
     public function providerFileCheckerValidCodeParse()
     {
         return [
-            'doesNothing' => [
+            'addMissingVoidReturnType56' => [
                 '<?php
                     function foo() { }',
                 '<?php
@@ -86,8 +96,29 @@ class FileManipulationTest extends TestCase
                      * @return void
                      */
                     function foo() { }',
+                '5.6',
+                ['MissingReturnType'],
             ],
-            'returnsString' => [
+            'addMissingVoidReturnType70' => [
+                '<?php
+                    function foo() { }',
+                '<?php
+                    /**
+                     * @return void
+                     */
+                    function foo() { }',
+                '7.0',
+                ['MissingReturnType'],
+            ],
+            'addMissingVoidReturnType71' => [
+                '<?php
+                    function foo() { }',
+                '<?php
+                    function foo() : void { }',
+                '7.1',
+                ['MissingReturnType'],
+            ],
+            'addMissingStringReturnType56' => [
                 '<?php
                     function foo() {
                         return "hello";
@@ -99,8 +130,98 @@ class FileManipulationTest extends TestCase
                     function foo() {
                         return "hello";
                     }',
+                '5.6',
+                ['MissingReturnType'],
             ],
-            'returnsStringNotInt' => [
+            'addMissingStringReturnType70' => [
+                '<?php
+                    function foo() {
+                        return "hello";
+                    }',
+                '<?php
+                    function foo() : string {
+                        return "hello";
+                    }',
+                '7.0',
+                ['MissingReturnType'],
+            ],
+            'addMissingNullableStringReturnType56' => [
+                '<?php
+                    function foo() {
+                        return rand(0, 1) ? "hello" : null;
+                    }',
+                '<?php
+                    /**
+                     * @return string|null
+                     */
+                    function foo() {
+                        return rand(0, 1) ? "hello" : null;
+                    }',
+                '5.6',
+                ['MissingReturnType'],
+            ],
+            'addMissingStringReturnType70' => [
+                '<?php
+                    function foo() {
+                        return rand(0, 1) ? "hello" : null;
+                    }',
+                '<?php
+                    /**
+                     * @return string|null
+                     */
+                    function foo() {
+                        return rand(0, 1) ? "hello" : null;
+                    }',
+                '7.0',
+                ['MissingReturnType'],
+            ],
+            'addMissingStringReturnType71' => [
+                '<?php
+                    function foo() {
+                        return rand(0, 1) ? "hello" : null;
+                    }',
+                '<?php
+                    function foo() : ?string {
+                        return rand(0, 1) ? "hello" : null;
+                    }',
+                '7.1',
+                ['MissingReturnType'],
+            ],
+            'addMissingStringArrayReturnType56' => [
+                '<?php
+                    function foo() {
+                        return ["hello"];
+                    }',
+                '<?php
+                    /**
+                     * @return string[]
+                     *
+                     * @psalm-return array{0:string}
+                     */
+                    function foo() {
+                        return ["hello"];
+                    }',
+                '5.6',
+                ['MissingReturnType'],
+            ],
+            'addMissingStringArrayReturnType70' => [
+                '<?php
+                    function foo() {
+                        return ["hello"];
+                    }',
+                '<?php
+                    /**
+                     * @return string[]
+                     *
+                     * @psalm-return array{0:string}
+                     */
+                    function foo() : array {
+                        return ["hello"];
+                    }',
+                '7.0',
+                ['MissingReturnType'],
+            ],
+            'fixInvalidIntReturnType56' => [
                 '<?php
                     /**
                      * @return int
@@ -115,20 +236,26 @@ class FileManipulationTest extends TestCase
                     function foo() {
                         return "hello";
                     }',
+                '5.6',
+                ['InvalidReturnType'],
             ],
-            'returnStringArray' => [
+            'fixInvalidIntReturnType70' => [
                 '<?php
-                    function foo() {
-                        return ["hello"];
+                    /**
+                     * @return int
+                     */
+                    function foo() : int {
+                        return "hello";
                     }',
                 '<?php
                     /**
-                     * @return       string[]
-                     * @psalm-return array{0:string}
+                     * @return string
                      */
-                    function foo() {
-                        return ["hello"];
+                    function foo() : string {
+                        return "hello";
                     }',
+                '7.0',
+                ['InvalidReturnType'],
             ],
             'useUnqualifierPlugin' => [
                 '<?php
@@ -149,6 +276,8 @@ class FileManipulationTest extends TestCase
 
                         new D();
                     }',
+                PHP_VERSION,
+                [],
             ],
         ];
     }