Try to rework abs to return the same type passed in.

src/core/Any-num.pm

@@ -1,7 +1,6 @@
 augment class Any {
-
-    method abs() is export {
-        pir::abs__Nn(self);
+    multi method abs() {
+        self.Num.abs;
     }
 
     multi method exp() {
@@ -174,7 +173,8 @@ augment class Any {
     }
 }
 
-our multi sub abs($x) { (+$x).abs }
+our proto sub abs($x) { $x.abs }
+our multi sub prefix:<abs>($x) { $x.abs }
 our proto sub exp($exponent) { $exponent.exp }
 our proto sub log($x) { $x.log }
 our proto sub log10($x) { $x.log10 }

src/core/Complex.pm

@@ -234,8 +234,6 @@ class Complex {
     }
 }
 
-multi sub abs(Complex $x) { $x.abs }
-
 multi sub infix:<+>(Complex $a, Complex $b) {
     Complex.new($a.re + $b.re, $a.im + $b.im);
 }

src/core/Int.pm

@@ -15,7 +15,7 @@ our sub upgrade_to_num_if_needed($test) {
 
 augment class Int {
     multi method abs() {
-        pir::box__PI(pir::abs__II(self))
+        self < 0 ?? -self !! self;
     }
 
     our Int multi method Int() { self }
@@ -45,8 +45,6 @@ augment class Int {
     }
 }
 
-our multi sub abs(Int $x) { $x.abs }
-
 our multi sub infix:<+>(Int $a, Int $b) {
     upgrade_to_num_if_needed(pir::add__NNN($a, $b))
 }

src/core/Num.pm

@@ -11,6 +11,10 @@ augment class Num {
 
     multi method Num() { self; }
 
+    multi method abs() {
+        pir::abs__Nn(self);
+    }
+
     multi method exp() {
         pir::exp__Nn(self);
     }

src/core/Rat.pm

@@ -52,6 +52,10 @@ class Rat {
         Rat.new($!numerator - $!denominator, $!denominator);
     }
 
+    multi method abs() {
+        self < 0 ?? -self !! self;
+    }
+
     our Int multi method sign {
         # self ~~ NaN ?? NaN !! self <=> 0;
         self < 0 ?? -1 !! ( self == 0 ?? 0 !! 1);