1 files changed, 17 insertions, 3 deletions
diff --git a/lib/pure/rationals.nim b/lib/pure/rationals.nim
index 04aa8316a..3b68a2381 100644
--- a/lib/pure/rationals.nim
+++ b/lib/pure/rationals.nim
@@ -12,6 +12,7 @@
 ## a denominator `den`, both of type int. The denominator can not be 0.
 
 import math
+import hashes
 
 type Rational*[T] = object
   ## a rational number, consisting of a numerator and denominator
@@ -32,7 +33,7 @@ proc `$`*[T](x: Rational[T]): string =
   ## Turn a rational number into a string.
   result = $x.num & "/" & $x.den
 
-proc toRational*[T](x: SomeInteger): Rational[T] =
+proc toRational*[T](x: T): Rational[T] =
   ## Convert some integer `x` to a rational number.
   result.num = x
   result.den = 1
@@ -188,7 +189,7 @@ proc `/=`*[T](x: var Rational[T], y: T) =
   x.den *= y
   reduce(x)
 
-proc cmp*(x, y: Rational): int =
+proc cmp*(x, y: Rational): int {.procvar.} =
   ## Compares two rationals.
   (x - y).num
 
@@ -205,6 +206,17 @@ proc abs*[T](x: Rational[T]): Rational[T] =
   result.num = abs x.num
   result.den = abs x.den
 
+proc hash*[T](x: Rational[T]): THash =
+  ## Computes hash for rational `x`
+  # reduce first so that hash(x) == hash(y) for x == y
+  var copy = x
+  reduce(copy)
+
+  var h: THash = 0
+  h = h !& hash(copy.num)
+  h = h !& hash(copy.den)
+  result = !$h
+  
 when isMainModule:
   var
     z = Rational[int](num: 0, den: 1)
@@ -242,11 +254,13 @@ when isMainModule:
   assert( not(o > o) )
   assert( cmp(o, o) == 0 )
   assert( cmp(z, z) == 0 )
+  assert( hash(o) == hash(o) )
 
   assert( a == b )
   assert( a >= b )
   assert( not(b > a) )
   assert( cmp(a, b) == 0 )
+  assert( hash(a) == hash(b) )
 
   var x = 1//3
 
@@ -270,6 +284,6 @@ when isMainModule:
   y /= 9
   assert( y == 13//27 )
 
-  assert toRational[int, int](5) == 5//1
+  assert toRational(5) == 5//1
   assert abs(toFloat(y) - 0.4814814814814815) < 1.0e-7
   assert toInt(z) == 0