[zsh] Move func/ directory to zsh/functions

zsh/functions/bool

@@ -0,0 +1,31 @@
+# Eryn Wells <eryn@erynwells.me>
+# vim: set ft=zsh:
+
+function bool {
+    if [[ "$1" =~ '^-?[0-9]+$' ]]; then
+        if (( $1 == 0 )); then
+            echo "no"
+            return 1
+        else
+            echo "yes"
+            return 0
+        fi
+    fi
+
+    local lowercase_value=${(L)1}
+
+    if [[ "$lowercase_value" == "yes" || "$lowercase_value" == "true" ]]; then
+        echo "yes"
+        return 0
+    fi
+
+    if [[ "$lowercase_value" == "no" || "$lowercase_value" == "false" ]]; then
+        echo "no"
+        return 1
+    fi
+
+    echo "no"
+    return 1
+}
+
+bool "$@"