Add the 'unset' built-in command

Add the 'unset' command to remove global environment variable
definitions from the shell.

1 files changed, 15 insertions, 0 deletions

diff --git a/src/poem/anthology/export.rs b/src/poem/anthology/export.rs
index 76dfd99..a61935c 100644
--- a/src/poem/anthology/export.rs
+++ b/src/poem/anthology/export.rs
@@ -21,3 +21,18 @@ pub fn incant(verse: &Verse) -> i32 {
 
     0
 }
+
+pub fn unincant(verse: &Verse) -> i32 {
+    match verse.clause() {
+        Some(clause) => {
+            for stanza in clause {
+                env::remove_var(stanza);
+            }
+        }
+        None => {
+            eprintln!("unset: not enough arguments");
+            return 1;
+        }
+    }
+    0
+}