diff --git a/src/Call.php b/src/Call.php
index 2a5335d..420dab8 100644
--- a/src/Call.php
+++ b/src/Call.php
@@ -34,6 +34,7 @@ public function __construct(
         public readonly Type $type,
         public readonly array $arguments,
         Span $location,
+        public readonly CallType $callType = CallType::Method,
     ) {
         $this->location = $location;
     }
@@ -58,8 +59,12 @@ private static function compareArguments(array $a, array $b): bool
 
     public function __toString(): string
     {
-        /** @psalm-suppress ImplicitToStringCast */
-        return sprintf('%s.%s:%s(%s)', $this->target, $this->name, $this->type, implode(', ', $this->arguments));
+        return match ($this->callType) {
+            CallType::Infix => sprintf('%s %s %s', $this->target, $this->name, $this->arguments[0]),
+            CallType::Prefix => sprintf('%s%s', $this->name, $this->target),
+            /** @psalm-suppress ImplicitToStringCast */
+            CallType::Method => sprintf('%s.%s:%s(%s)', $this->target, $this->name, $this->type, implode(', ', $this->arguments)),
+        };
     }
 
     public function evaluate(Scope $scope): mixed
diff --git a/src/CallType.php b/src/CallType.php
new file mode 100644
index 0000000..69e75e6
--- /dev/null
+++ b/src/CallType.php
@@ -0,0 +1,12 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Eventjet\Ausdruck;
+
+enum CallType
+{
+    case Method;
+    case Infix;
+    case Prefix;
+}
diff --git a/src/Eq.php b/src/Eq.php
deleted file mode 100644
index e3d37f0..0000000
--- a/src/Eq.php
+++ /dev/null
@@ -1,53 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace Eventjet\Ausdruck;
-
-use Eventjet\Ausdruck\Parser\Span;
-
-use function sprintf;
-
-/**
- * @extends Expression<bool>
- * @internal
- * @psalm-internal Eventjet\Ausdruck
- */
-final class Eq extends Expression
-{
-    /**
-     * @param Expression<mixed> $left
-     * @param Expression<mixed> $right
-     */
-    public function __construct(public readonly Expression $left, public readonly Expression $right)
-    {
-    }
-
-    public function __toString(): string
-    {
-        /** @psalm-suppress ImplicitToStringCast */
-        return sprintf('%s === %s', $this->left, $this->right);
-    }
-
-    public function evaluate(Scope $scope): bool
-    {
-        return $this->left->evaluate($scope) === $this->right->evaluate($scope);
-    }
-
-    public function equals(Expression $other): bool
-    {
-        return $other instanceof self
-            && $this->left->equals($other->left)
-            && $this->right->equals($other->right);
-    }
-
-    public function getType(): Type
-    {
-        return Type::bool();
-    }
-
-    public function location(): Span
-    {
-        return $this->left->location()->to($this->right->location());
-    }
-}
diff --git a/src/Expr.php b/src/Expr.php
index 41823b5..4953dcf 100644
--- a/src/Expr.php
+++ b/src/Expr.php
@@ -26,10 +26,11 @@ private function __construct()
      * @template T
      * @param Expression<T> $left
      * @param Expression<T> $right
+     * @return Expression<bool>
      */
-    public static function eq(Expression $left, Expression $right): Eq
+    public static function eq(Expression $left, Expression $right): Expression
     {
-        return new Eq($left, $right);
+        return new Call($left, '===', Type::bool(), [$right], $left->location()->to($right->location()), CallType::Infix);
     }
 
     /**
@@ -80,10 +81,11 @@ public static function call(Expression $target, string $name, Type $type, array
     /**
      * @param Expression<bool> $left
      * @param Expression<bool> $right
+     * @return Expression<bool>
      */
-    public static function or_(Expression $left, Expression $right): Or_
+    public static function or_(Expression $left, Expression $right): Expression
     {
-        return new Or_($left, $right);
+        return new Call($left, '||', Type::bool(), [$right], $left->location()->to($right->location()), CallType::Infix);
     }
 
     /**
@@ -103,32 +105,40 @@ public static function lambda(Expression $body, array $parameters = [], Span|nul
      * @template T of int | float
      * @param Expression<T> $minuend
      * @param Expression<T> $subtrahend
-     * @return Subtract<T>
+     * @return Expression<T>
      */
-    public static function subtract(Expression $minuend, Expression $subtrahend): Subtract
+    public static function subtract(Expression $minuend, Expression $subtrahend): Expression
     {
-        return new Subtract($minuend, $subtrahend);
+        return new Call(
+            $minuend,
+            '-',
+            $minuend->getType(),
+            [$subtrahend],
+            $minuend->location()->to($subtrahend->location()),
+            CallType::Infix,
+        );
     }
 
     /**
      * @template T of int | float
      * @param Expression<T> $left
      * @param Expression<T> $right
-     * @return Gt<T>
+     * @return Expression<bool>
      */
-    public static function gt(Expression $left, Expression $right): Gt
+    public static function gt(Expression $left, Expression $right): Expression
     {
-        return new Gt($left, $right);
+        return new Call($left, '>', Type::bool(), [$right], $left->location()->to($right->location()), CallType::Infix);
     }
 
     /**
      * @template T of int | float
      * @param Expression<T> $expression
-     * @return Negative<T>
+     * @return Expression<T>
      */
-    public static function negative(Expression $expression, Span|null $location = null): Negative
+    public static function negative(Expression $expression, Span|null $location = null): Expression
     {
-        return new Negative($expression, $location ?? self::dummySpan());
+        $location ??= self::dummySpan();
+        return new Call($expression, '-', $expression->getType(), [], $location, CallType::Prefix);
     }
 
     private static function dummySpan(): Span
diff --git a/src/Expression.php b/src/Expression.php
index 1d192bd..56a5be8 100644
--- a/src/Expression.php
+++ b/src/Expression.php
@@ -15,8 +15,9 @@ abstract class Expression implements Stringable
 {
     /**
      * @param self<mixed> $other
+     * @return Expression<bool>
      */
-    public function eq(self $other): Eq
+    public function eq(self $other): self
     {
         return Expr::eq($this, $other);
     }
@@ -24,9 +25,9 @@ public function eq(self $other): Eq
     /**
      * @template U of int | float
      * @param Expression<U> $subtrahend
-     * @return Subtract<U>
+     * @return Expression<U>
      */
-    public function subtract(self $subtrahend): Subtract
+    public function subtract(self $subtrahend): self
     {
         /** @var self<U> $self */
         $self = $this;
@@ -36,9 +37,9 @@ public function subtract(self $subtrahend): Subtract
     /**
      * @template U of int | float
      * @param Expression<U> $right
-     * @return Gt<U>
+     * @return Expression<bool>
      */
-    public function gt(self $right): Gt
+    public function gt(self $right): self
     {
         /** @var self<U> $self */
         $self = $this;
@@ -47,8 +48,9 @@ public function gt(self $right): Gt
 
     /**
      * @param self<bool> $other
+     * @return Expression<bool>
      */
-    public function or_(self $other): Or_
+    public function or_(self $other): self
     {
         /** @var self<bool> $self */
         $self = $this;
diff --git a/src/Gt.php b/src/Gt.php
deleted file mode 100644
index 69cf300..0000000
--- a/src/Gt.php
+++ /dev/null
@@ -1,54 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace Eventjet\Ausdruck;
-
-use Eventjet\Ausdruck\Parser\Span;
-
-use function sprintf;
-
-/**
- * @template T of int | float
- * @extends Expression<bool>
- * @internal
- * @psalm-internal Eventjet\Ausdruck
- */
-final class Gt extends Expression
-{
-    /**
-     * @param Expression<T> $left
-     * @param Expression<T> $right
-     */
-    public function __construct(private readonly Expression $left, private readonly Expression $right)
-    {
-    }
-
-    public function __toString(): string
-    {
-        /** @psalm-suppress ImplicitToStringCast */
-        return sprintf('%s > %s', $this->left, $this->right);
-    }
-
-    public function evaluate(Scope $scope): bool
-    {
-        return $this->left->evaluate($scope) > $this->right->evaluate($scope);
-    }
-
-    public function equals(Expression $other): bool
-    {
-        return $other instanceof self
-            && $this->left->equals($other->left)
-            && $this->right->equals($other->right);
-    }
-
-    public function getType(): Type
-    {
-        return Type::bool();
-    }
-
-    public function location(): Span
-    {
-        return $this->left->location()->to($this->right->location());
-    }
-}
diff --git a/src/Negative.php b/src/Negative.php
deleted file mode 100644
index e853de6..0000000
--- a/src/Negative.php
+++ /dev/null
@@ -1,51 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace Eventjet\Ausdruck;
-
-use Eventjet\Ausdruck\Parser\Span;
-
-use function sprintf;
-
-/**
- * @template T of int | float
- * @extends Expression<T>
- */
-final class Negative extends Expression
-{
-    use LocationTrait;
-
-    /**
-     * @param Expression<T> $expression
-     */
-    public function __construct(public readonly Expression $expression, Span $location)
-    {
-        $this->location = $location;
-    }
-
-    public function __toString(): string
-    {
-        return sprintf('-%s', $this->expression);
-    }
-
-    /**
-     * @psalm-suppress InvalidReturnType False positive
-     */
-    public function evaluate(Scope $scope): float|int
-    {
-        /** @psalm-suppress InvalidReturnStatement False positive */
-        return -$this->expression->evaluate($scope);
-    }
-
-    public function equals(Expression $other): bool
-    {
-        return $other instanceof self
-            && $this->expression->equals($other->expression);
-    }
-
-    public function getType(): Type
-    {
-        return $this->expression->getType();
-    }
-}
diff --git a/src/Or_.php b/src/Or_.php
deleted file mode 100644
index 2520f61..0000000
--- a/src/Or_.php
+++ /dev/null
@@ -1,53 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace Eventjet\Ausdruck;
-
-use Eventjet\Ausdruck\Parser\Span;
-
-use function sprintf;
-
-/**
- * @extends Expression<bool>
- * @internal
- * @psalm-internal Eventjet\Ausdruck
- */
-final class Or_ extends Expression
-{
-    /**
-     * @param Expression<bool> $left
-     * @param Expression<bool> $right
-     */
-    public function __construct(public readonly Expression $left, public readonly Expression $right)
-    {
-    }
-
-    public function __toString(): string
-    {
-        /** @psalm-suppress ImplicitToStringCast */
-        return sprintf('%s || %s', $this->left, $this->right);
-    }
-
-    public function evaluate(Scope $scope): bool
-    {
-        return $this->left->evaluate($scope) || $this->right->evaluate($scope);
-    }
-
-    public function equals(Expression $other): bool
-    {
-        return $other instanceof self
-            && $this->left->equals($other->left)
-            && $this->right->equals($other->right);
-    }
-
-    public function getType(): Type
-    {
-        return Type::bool();
-    }
-
-    public function location(): Span
-    {
-        return $this->left->location()->to($this->right->location());
-    }
-}
diff --git a/src/Scope.php b/src/Scope.php
index 50eeab0..3607fb3 100644
--- a/src/Scope.php
+++ b/src/Scope.php
@@ -41,6 +41,10 @@ final class Scope
     public function __construct(private readonly array $vars = [], array $funcs = [], private readonly Scope|null $parent = null)
     {
         $predefinedFuncs = $this->parent === null ? [
+            '||' => self::or(...),
+            '===' => self::eq(...),
+            '-' => self::subtract(...),
+            '>' => self::gt(...),
             'contains' => self::contains(...),
             'count' => self::count(...),
             'filter' => self::filter(...),
@@ -193,6 +197,33 @@ private static function identity(mixed $value): mixed
         return $value;
     }
 
+    private static function or(bool $left, bool $right): bool
+    {
+        return $left || $right;
+    }
+
+    private static function eq(mixed $left, mixed $right): bool
+    {
+        return $left === $right;
+    }
+
+    /**
+     * @return ($minuend is float ? float : ($subtrahend is float ? float : int))
+     */
+    private static function subtract(int|float $minuend, int|float|null $subtrahend = null): int|float
+    {
+        if ($subtrahend === null) {
+            return -$minuend;
+        }
+        /** @psalm-suppress InvalidOperand */
+        return $minuend - $subtrahend;
+    }
+
+    private static function gt(int|float $left, int|float $right): bool
+    {
+        return $left > $right;
+    }
+
     /**
      * @internal
      */
diff --git a/src/Subtract.php b/src/Subtract.php
deleted file mode 100644
index c8dbfc7..0000000
--- a/src/Subtract.php
+++ /dev/null
@@ -1,61 +0,0 @@
-<?php
-
-declare(strict_types=1);
-
-namespace Eventjet\Ausdruck;
-
-use Eventjet\Ausdruck\Parser\Span;
-
-use function sprintf;
-
-/**
- * @template T of int | float
- * @extends Expression<T>
- * @internal
- * @psalm-internal Eventjet\Ausdruck
- */
-final class Subtract extends Expression
-{
-    /**
-     * @param Expression<T> $minuend
-     * @param Expression<T> $subtrahend
-     */
-    public function __construct(public readonly Expression $minuend, public readonly Expression $subtrahend)
-    {
-    }
-
-    public function __toString(): string
-    {
-        /** @psalm-suppress ImplicitToStringCast */
-        return sprintf('%s - %s', $this->minuend, $this->subtrahend);
-    }
-
-    /**
-     * @psalm-suppress InvalidReturnType False positive
-     */
-    public function evaluate(Scope $scope): int|float
-    {
-        /**
-         * @psalm-suppress InvalidOperand False positive; they are guaranteed to have the same type
-         * @psalm-suppress InvalidReturnStatement False positive
-         */
-        return $this->minuend->evaluate($scope) - $this->subtrahend->evaluate($scope);
-    }
-
-    public function equals(Expression $other): bool
-    {
-        return $other instanceof self
-            && $this->minuend->equals($other->minuend)
-            && $this->subtrahend->equals($other->subtrahend);
-    }
-
-    public function getType(): Type
-    {
-        return $this->minuend->getType();
-    }
-
-    public function location(): Span
-    {
-        return $this->minuend->location()->to($this->subtrahend->location());
-    }
-}
diff --git a/tests/unit/ExpressionComparisonTest.php b/tests/unit/ExpressionComparisonTest.php
index 5ee7664..14d1621 100644
--- a/tests/unit/ExpressionComparisonTest.php
+++ b/tests/unit/ExpressionComparisonTest.php
@@ -5,18 +5,13 @@
 namespace Eventjet\Ausdruck\Test\Unit;
 
 use Eventjet\Ausdruck\Call;
-use Eventjet\Ausdruck\Eq;
 use Eventjet\Ausdruck\Expr;
 use Eventjet\Ausdruck\Expression;
 use Eventjet\Ausdruck\Get;
-use Eventjet\Ausdruck\Gt;
 use Eventjet\Ausdruck\Lambda;
 use Eventjet\Ausdruck\ListLiteral;
 use Eventjet\Ausdruck\Literal;
-use Eventjet\Ausdruck\Negative;
-use Eventjet\Ausdruck\Or_;
 use Eventjet\Ausdruck\Parser\Span;
-use Eventjet\Ausdruck\Subtract;
 use Eventjet\Ausdruck\Type;
 use PHPUnit\Framework\TestCase;
 
@@ -66,15 +61,15 @@ public static function equalsCases(): iterable
      */
     public static function notEqualsCases(): iterable
     {
-        yield Eq::class . ': left is different' => [
+        yield '===: left is different' => [
             Expr::eq(Expr::literal('a'), Expr::literal('a')),
             Expr::eq(Expr::literal('b'), Expr::literal('a')),
         ];
-        yield Eq::class . ': right is different' => [
+        yield '===: right is different' => [
             Expr::eq(Expr::literal('a'), Expr::literal('a')),
             Expr::eq(Expr::literal('a'), Expr::literal('b')),
         ];
-        yield Eq::class . ': different type' => [
+        yield '===: different type' => [
             Expr::eq(Expr::literal('a'), Expr::literal('a')),
             Expr::or_(Expr::literal(true), Expr::literal(false)),
         ];
@@ -90,15 +85,15 @@ public static function notEqualsCases(): iterable
             Expr::get('a', Type::string()),
             Expr::literal('a'),
         ];
-        yield Lambda::class .': different number of parameters' => [
+        yield Lambda::class . ': different number of parameters' => [
             Expr::lambda(Expr::literal(true), ['foo']),
             Expr::lambda(Expr::literal(true), ['foo', 'bar']),
         ];
-        yield Lambda::class .': different parameter' => [
+        yield Lambda::class . ': different parameter' => [
             Expr::lambda(Expr::literal(true), ['a', 'b', 'c']),
             Expr::lambda(Expr::literal(true), ['a', 'x', 'c']),
         ];
-        yield Lambda::class .': different body' => [
+        yield Lambda::class . ': different body' => [
             Expr::lambda(Expr::literal(true), ['a', 'b', 'c']),
             Expr::lambda(Expr::literal(false), ['a', 'b', 'c']),
         ];
@@ -114,35 +109,35 @@ public static function notEqualsCases(): iterable
             Expr::literal('foo'),
             Expr::get('foo', Type::string()),
         ];
-        yield Or_::class . ': left is different' => [
+        yield '||: left is different' => [
             Expr::or_(Expr::literal(true), Expr::literal(false)),
             Expr::or_(Expr::literal(false), Expr::literal(false)),
         ];
-        yield Or_::class . ': right is different' => [
+        yield '||: right is different' => [
             Expr::or_(Expr::literal(true), Expr::literal(false)),
             Expr::or_(Expr::literal(true), Expr::literal(true)),
         ];
-        yield Or_::class . ': both are different' => [
+        yield '||: both are different' => [
             Expr::or_(Expr::literal(true), Expr::literal(false)),
             Expr::or_(Expr::literal(false), Expr::literal(true)),
         ];
-        yield Or_::class . ': different type' => [
+        yield '||: different type' => [
             Expr::or_(Expr::literal(true), Expr::literal(false)),
             Expr::eq(Expr::literal(true), Expr::literal(false)),
         ];
-        yield Subtract::class . ': minuend is different' => [
+        yield '-: minuend is different' => [
             Expr::subtract(Expr::literal(1), Expr::literal(2)),
             Expr::subtract(Expr::literal(2), Expr::literal(2)),
         ];
-        yield Subtract::class . ': subtrahend is different' => [
+        yield '-: subtrahend is different' => [
             Expr::subtract(Expr::literal(1), Expr::literal(2)),
             Expr::subtract(Expr::literal(1), Expr::literal(1)),
         ];
-        yield Subtract::class . ': subtrahend and minuend are different' => [
+        yield '-: subtrahend and minuend are different' => [
             Expr::subtract(Expr::literal(1), Expr::literal(2)),
             Expr::subtract(Expr::literal(2), Expr::literal(1)),
         ];
-        yield Subtract::class . ': different type' => [
+        yield '-: different type' => [
             Expr::subtract(Expr::literal(1), Expr::literal(2)),
             Expr::literal(1),
         ];
@@ -170,27 +165,27 @@ public static function notEqualsCases(): iterable
             Expr::call(Expr::literal(1), 'foo', Type::int(), []),
             Expr::literal(1),
         ];
-        yield Gt::class . ': left is different' => [
+        yield '>: left is different' => [
             Expr::gt(Expr::literal(1), Expr::literal(2)),
             Expr::gt(Expr::literal(2), Expr::literal(2)),
         ];
-        yield Gt::class . ': right is different' => [
+        yield '>: right is different' => [
             Expr::gt(Expr::literal(1), Expr::literal(2)),
             Expr::gt(Expr::literal(1), Expr::literal(1)),
         ];
-        yield Gt::class . ': both are different' => [
+        yield '>: both are different' => [
             Expr::gt(Expr::literal(1), Expr::literal(2)),
             Expr::gt(Expr::literal(2), Expr::literal(1)),
         ];
-        yield Gt::class . ': different type' => [
+        yield '>: different type' => [
             Expr::gt(Expr::literal(1), Expr::literal(2)),
             Expr::eq(Expr::literal(1), Expr::literal(2)),
         ];
-        yield Negative::class . ': different type' => [
+        yield 'Negative: different type' => [
             Expr::negative(Expr::literal(1)),
             Expr::literal(1),
         ];
-        yield Negative::class . ': different expression' => [
+        yield 'Negative: different expression' => [
             Expr::negative(Expr::literal(1)),
             Expr::negative(Expr::literal(2)),
         ];
diff --git a/tests/unit/ExpressionTest.php b/tests/unit/ExpressionTest.php
index b51e4b2..81dbde4 100644
--- a/tests/unit/ExpressionTest.php
+++ b/tests/unit/ExpressionTest.php
@@ -220,6 +220,7 @@ public static function toStringCases(): iterable
         ];
         yield 'Any type' => ['myval:any', 'myval:any'];
         yield 'List literal' => ['["foo", "bar"]', '["foo", "bar"]'];
+        yield 'Negative variable' => ['-myval:int', '-myval:int'];
     }
 
     /**