QuickSort example

examples/quicksort.zrc

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+#!../bin/zrc
+%include list
+
+fn quicksort {
+	let {m pivot less equal greater vn x} {
+		set m = $argv(1)
+		# Bail out if only one elem in list
+		if {[llength $m] <= 1} {
+			return $m
+		}
+
+		set pivot = [lindex $m 0]
+		set less = [set equal := [set greater := [list]]]
+
+		# Iterate through list
+		foreach x {*}$m {
+			set x = [subst $x]
+			echo 'x=$x, pivot=$pivot'
+
+			# See what var to dereference
+			# (leq, eq or geq)
+			switch [expr {$x <=> $pivot}] {
+				case -1 { set vn = 'less'    }
+				case  0 { set vn = 'equal'   }
+				case  1 { set vn = 'greater' }
+			}
+			set $vn = '$$vn $x'
+		}
+		return "
+			[quicksort $less]
+			$equal
+			[quicksort $greater]"
+	}
+}
+
+set L = {8 6 4 2 1 3 5 7 9}
+
+# Main routine
+fn main {
+	set L = [quicksort $L]
+	foreach x {*}$L {
+		echo -n [subst $x] ' '
+	}
+	echo
+	return 0
+}; main