Adds rand-seed procedure, which will set the seed value for random number generation

README.md

@@ -189,7 +189,7 @@ Quote and list both have some syntactic sugar to create a shorthand for their us
 
 Implemented:
 
-`positive?`, `negative?`, `zero?`, `abs`, `floor`, `ceil`, `round`, `+`, `-`, `*`, `/`, `min`, `max`, `number->string`, `rune->string`, `rand`, `%`, `cos`, `sin`, `tan`, `sqrt`, `atan`, `sqrt`
+`positive?`, `negative?`, `zero?`, `abs`, `floor`, `ceil`, `round`, `+`, `-`, `*`, `/`, `min`, `max`, `number->string`, `rune->string`, `rand`, `rand-seed`, `%`, `cos`, `sin`, `tan`, `sqrt`, `atan`, `sqrt`
 
 
 <details>
@@ -218,7 +218,8 @@ Implemented:
     <li><code>(max [number...])</code>: <code>number</code></li>
     <li><code>(number->string [number] [[base: number]])</code>: <code>string</code></li>
     <li><code>(rune->string [number])</code>: <code>string</code></li>
-    <li><code>(rand [[max]] [[min]])</code>: <code>number</code>
+    <li><code>(rand [[max: number]] [[min: number]])</code>: <code>number</code>
+    <li><code>(rand-seed [number])</code>: <code>#t</code>
   </ul>
 </details>
 

lib.go

@@ -2618,8 +2618,18 @@ var stdLibrary = vars{
 		}
 		return make([]expression, 0)
 	},
+	"rand-seed": func(a ...expression) expression {
+		if len(a) == 0 {
+			return exception("'rand-seed' expected a number, no value was given")
+		}
+		seed, ok := a[0].(number)
+		if !ok {
+			return exception("'rand-seed' expected a number, a non-number value was given")
+		}
+		rand.Seed(int64(seed))
+		return true
+	},
 	"rand": func(a ...expression) expression {
-		rand.Seed(time.Now().UnixNano())
 		if len(a) == 0 {
 			// equal to: (rand 1 0)
 			return number(rand.Float64())

main.go

@@ -4,6 +4,7 @@ import (
 	"flag"
 	"fmt"
 	"io/ioutil"
+	"math/rand"
 	"os"
 	"os/exec"
 	"os/signal"
@@ -12,11 +13,12 @@ import (
 	"sort"
 	"strings"
 	"syscall"
+	"time"
 
 	ln "github.com/peterh/liner"
 )
 
-const version = "0.7.4"
+const version = "0.7.5"
 
 const globalLibPath = "/usr/local/lib/slope/modules/"
 
@@ -85,6 +87,7 @@ func Init() {
 	c := make(chan os.Signal)
 	signal.Notify(c, syscall.SIGINT)
 	go handleSignals(c)
+	rand.Seed(time.Now().UnixNano())
 }
 
 func outputResult(txt string) {

static.go

@@ -129,6 +129,7 @@ var usageStrings = map[string]string{
 	"pwd":                   "(pwd) => string\n\nReturns the current working directory as a string",
 	"quote":                 "(quote [expression...]) => bool",
 	"rand":                  "(rand [[max: number]] [[min: number]]) => number\n\nIf no arguments are given `rand` will produce a floating point number between 0 and 1. If only `max` is given, `rand` will produce a floating point number between 0 and `max`. If `max` and `min` are both given, `rand` will produce a floating point number between `min` and `max`. `max` is always exclusive (the value produced will always be less than `max`), while `min` is inclusize. To obtain integers use `floor`, `ceil`, or `round` on the result or `rand`",
+	"rand-seed":             "(rand-seed [number]) => #t\n\nSets the seed value for generating random numbers. The seed value defaults to the timestamp that is acquired when slope starts up. This procedure will over-ride that behavior to use the given seed",
 	"range":                 "(range [[count: number]] [[start: number]] [[step: number]]) => list\n\nIf no arguments are given an empty list will be returned. `count` should be a positive integer and represents the number of list items that will be produced by `range`. If no arguments other than `count` are given then a list from 0 -> count will be produced. To start at a number other than zero `start` can be given. To step by a value other than one, `step` can be given.\n\n\t(range) => ()\n\t(range 5) => (0 1 2 3 4)\n\t(range 5 10) => (10 11 12 13 14)\n\t(range 5 2 2) => (2 4 6 8 10)",
 	"read-all":              "(read-all [[IOHandle]]) => string\n\nReads all content from the given io-handle",
 	"read-all-lines":        "(read-all-lines [[IOHandle]]) => list\n\nReads all content from the given io-handle and splits it into a list on newline",