smalltalk: Number tower (Fraction, factorial, gcd:/lcm:, etc.) + 47 tests

lib/smalltalk/runtime.sx

@@ -369,6 +369,7 @@
       (st-class-define! "SmallInteger" "Integer" (list))
       (st-class-define! "LargePositiveInteger" "Integer" (list))
       (st-class-define! "Float" "Number" (list))
+      (st-class-define! "Fraction" "Number" (list "numerator" "denominator"))
       (st-class-define! "Character" "Magnitude" (list "value"))
       ;; Collections
       (st-class-define! "Collection" "Object" (list))
@@ -679,6 +680,76 @@
           "peek
              self atEnd ifTrue: [^ nil].
              ^ collection at: position + 1"))
+      ;; ── Fraction ──
+      ;; Rational numbers stored as numerator/denominator, normalized
+      ;; (sign on numerator, denominator > 0, reduced via gcd).
+      (st-class-add-class-method! "Fraction" "numerator:denominator:"
+        (st-parse-method
+          "numerator: n denominator: d
+             | f |
+             f := super new.
+             ^ f setNumerator: n denominator: d"))
+      (st-class-add-method! "Fraction" "setNumerator:denominator:"
+        (st-parse-method
+          "setNumerator: n denominator: d
+             | g s nn dd |
+             d = 0 ifTrue: [Error signal: 'Fraction denominator cannot be zero'].
+             s := (d < 0) ifTrue: [-1] ifFalse: [1].
+             nn := n * s. dd := d * s.
+             g := nn abs gcd: dd.
+             g = 0 ifTrue: [g := 1].
+             numerator := nn / g.
+             denominator := dd / g.
+             ^ self"))
+      (st-class-add-method! "Fraction" "numerator"
+        (st-parse-method "numerator ^ numerator"))
+      (st-class-add-method! "Fraction" "denominator"
+        (st-parse-method "denominator ^ denominator"))
+      (st-class-add-method! "Fraction" "+"
+        (st-parse-method
+          "+ other
+             ^ Fraction
+                 numerator: numerator * other denominator + (other numerator * denominator)
+                 denominator: denominator * other denominator"))
+      (st-class-add-method! "Fraction" "-"
+        (st-parse-method
+          "- other
+             ^ Fraction
+                 numerator: numerator * other denominator - (other numerator * denominator)
+                 denominator: denominator * other denominator"))
+      (st-class-add-method! "Fraction" "*"
+        (st-parse-method
+          "* other
+             ^ Fraction
+                 numerator: numerator * other numerator
+                 denominator: denominator * other denominator"))
+      (st-class-add-method! "Fraction" "/"
+        (st-parse-method
+          "/ other
+             ^ Fraction
+                 numerator: numerator * other denominator
+                 denominator: denominator * other numerator"))
+      (st-class-add-method! "Fraction" "negated"
+        (st-parse-method
+          "negated ^ Fraction numerator: numerator negated denominator: denominator"))
+      (st-class-add-method! "Fraction" "reciprocal"
+        (st-parse-method
+          "reciprocal ^ Fraction numerator: denominator denominator: numerator"))
+      (st-class-add-method! "Fraction" "="
+        (st-parse-method
+          "= other
+             ^ numerator = other numerator and: [denominator = other denominator]"))
+      (st-class-add-method! "Fraction" "<"
+        (st-parse-method
+          "< other
+             ^ numerator * other denominator < (other numerator * denominator)"))
+      (st-class-add-method! "Fraction" "asFloat"
+        (st-parse-method "asFloat ^ numerator / denominator"))
+      (st-class-add-method! "Fraction" "printString"
+        (st-parse-method
+          "printString ^ numerator printString , '/' , denominator printString"))
+      (st-class-add-method! "Fraction" "isFraction"
+        (st-parse-method "isFraction ^ true"))
       "ok")))
 
 ;; Initialise on load. Tests can re-bootstrap to reset state.