use generics in random (nim-lang#16283)

* use generics in random

* fix

lib/pure/random.nim

@@ -217,8 +217,7 @@ proc rand*(r: var Rand; max: Natural): int {.benign.} =
   ## Returns a random integer in the range `0..max` using the given state.
   ##
   ## See also:
-  ## * `rand proc<#rand,int>`_ that returns an integer using the default
-  ##   random number generator
+  ## * `rand proc<#rand,T>`_ `T` are integers, floats, and enums without holes.
   ## * `rand proc<#rand,Rand,range[]>`_ that returns a float
   ## * `rand proc<#rand,Rand,HSlice[T,T]>`_ that accepts a slice
   ## * `rand proc<#rand,typedesc[T]>`_ that accepts an integer or range type
@@ -233,28 +232,6 @@ proc rand*(r: var Rand; max: Natural): int {.benign.} =
     if x <= randMax - (randMax mod Ui(max)):
       return int(x mod (uint64(max)+1u64))
 
-proc rand*(max: int): int {.benign.} =
-  ## Returns a random integer in the range `0..max`.
-  ##
-  ## If `randomize<#randomize>`_ has not been called, the sequence of random
-  ## numbers returned from this proc will always be the same.
-  ##
-  ## This proc uses the default random number generator. Thus, it is **not**
-  ## thread-safe.
-  ##
-  ## See also:
-  ## * `rand proc<#rand,Rand,Natural>`_ that returns an integer using a
-  ##   provided state
-  ## * `rand proc<#rand,float>`_ that returns a float
-  ## * `rand proc<#rand,HSlice[T,T]>`_ that accepts a slice
-  ## * `rand proc<#rand,typedesc[T]>`_ that accepts an integer or range type
-  runnableExamples:
-    randomize(123)
-    doAssert rand(100) == 0
-    doAssert rand(100) == 96
-    doAssert rand(100) == 66
-  rand(state, max)
-
 proc rand*(r: var Rand; max: range[0.0 .. high(float)]): float {.benign.} =
   ## Returns a random floating point number in the range `0.0..max`
   ## using the given state.
@@ -276,8 +253,10 @@ proc rand*(r: var Rand; max: range[0.0 .. high(float)]): float {.benign.} =
     let u = (0x3FFu64 shl 52u64) or (x shr 12u64)
     result = (cast[float](u) - 1.0) * max
 
-proc rand*(max: float): float {.benign.} =
-  ## Returns a random floating point number in the range `0.0..max`.
+proc rand*[T: Ordinal or SomeFloat](max: T): T {.benign.} =
+  ## Returns a random floating point number in the range `T(0) .. max`.
+  ## 
+  ## Allowed types for `T` are integers, floats, and enums without holes.
   ##
   ## If `randomize<#randomize>`_ has not been called, the sequence of random
   ## numbers returned from this proc will always be the same.
@@ -286,16 +265,21 @@ proc rand*(max: float): float {.benign.} =
   ## thread-safe.
   ##
   ## See also:
+  ## * `rand proc<#rand,Rand,Natural>`_ that returns an integer using a
+  ##   provided state
   ## * `rand proc<#rand,Rand,range[]>`_ that returns a float using a
   ##   provided state
-  ## * `rand proc<#rand,int>`_ that returns an integer
   ## * `rand proc<#rand,HSlice[T,T]>`_ that accepts a slice
   ## * `rand proc<#rand,typedesc[T]>`_ that accepts an integer or range type
   runnableExamples:
-    randomize(234)
+    randomize(123)
+    doAssert rand(100) == 0
+    doAssert rand(100) == 96
+    doAssert rand(100) == 66
+
     let f = rand(1.0)
     ## f = 8.717181376738381e-07
-  rand(state, max)
+  result = T(rand(state, max))
 
 proc rand*[T: Ordinal or SomeFloat](r: var Rand; x: HSlice[T, T]): T =
   ## For a slice `a..b`, returns a value in the range `a..b` using the given
@@ -335,8 +319,7 @@ proc rand*[T: Ordinal or SomeFloat](x: HSlice[T, T]): T =
   ## See also:
   ## * `rand proc<#rand,Rand,HSlice[T,T]>`_ that accepts a slice and uses
   ##   a provided state
-  ## * `rand proc<#rand,int>`_ that returns an integer
-  ## * `rand proc<#rand,float>`_ that returns a floating point number
+  ## * `rand proc<#rand,T>`_ `T` are integers, floats, and enums without holes.
   ## * `rand proc<#rand,typedesc[T]>`_ that accepts an integer or range type
   runnableExamples:
     randomize(345)
@@ -355,8 +338,7 @@ proc rand*[T: SomeInteger](t: typedesc[T]): T =
   ## thread-safe.
   ##
   ## See also:
-  ## * `rand proc<#rand,int>`_ that returns an integer
-  ## * `rand proc<#rand,float>`_ that returns a floating point number
+  ## * `rand proc<#rand,T>`_ `T` are integers, floats, and enums without holes.
   ## * `rand proc<#rand,HSlice[T,T]>`_ that accepts a slice
   runnableExamples:
     randomize(567)