diff --git a/lib/functions.zsh b/lib/functions.zsh
index 63ab755c..aaf8a03e 100644
--- a/lib/functions.zsh
+++ b/lib/functions.zsh
@@ -15,3 +15,61 @@ function take() {
   cd $1
 }
 
+#
+# Get the value of an alias.
+#
+# Arguments:
+#    1. alias - The alias to get its value from
+# STDOUT:
+#    The value of alias $1 (if it has one).
+# Return value:
+#    0 if the alias was found,
+#    1 if it does not exist
+#
+function alias_value() {
+    alias "$1" | sed "s/^$1='\(.*\)'$/\1/"
+    test $(alias "$1")
+}
+
+#
+# Try to get the value of an alias,
+# otherwise return the input.
+#
+# Arguments:
+#    1. alias - The alias to get its value from
+# STDOUT:
+#    The value of alias $1, or $1 if there is no alias $1.
+# Return value:
+#    Always 0
+#
+function try_alias_value() {
+    alias_value "$1" || echo "$1"
+}
+
+#
+# Set variable "$1" to default value "$2" if "$1" is not yet defined.
+#
+# Arguments:
+#    1. name - The variable to set
+#    2. val  - The default value 
+# Return value:
+#    0 if the variable exists, 3 if it was set
+#
+function default() {
+    test `typeset +m "$1"` && return 0
+    typeset -g "$1"="$2"   && return 3
+}
+
+#
+# Set enviroment variable "$1" to default value "$2" if "$1" is not yet defined.
+#
+# Arguments:
+#    1. name - The env variable to set
+#    2. val  - The default value 
+# Return value:
+#    0 if the env variable exists, 3 if it was set
+#
+function env_default() {
+    env | grep -q "^$1=" && return 0 
+    export "$1=$2"       && return 3
+}