add list type check

Readme.org

@@ -155,7 +155,6 @@ Note: this section only tracks the state of incomplete TODO items. Having everyt
 ** DONE Beta tasks
 (See tag: v0.3.0)
 ** TODO v1.0 tasks
-- islist type query
 - set library
 - Can pass args to relish scripts (via interpreter)
 - Can pass args to relish scripts (via command line)

Writing.org

@@ -299,7 +299,7 @@ The following table is up to date as of Relish 0.3.0. For latest information try
 |----------------+---------------+----------------+---------+--------+-----------+-----------+-----------+--------+-------------|
 |                |               |                | pop     | gte?   | string    |           | cond      |        |             |
 |----------------+---------------+----------------+---------+--------+-----------+-----------+-----------+--------+-------------|
-|                |               |                |         | int    |           |           |           |        |             |
+|                |               |                | list?   | int    |           |           |           |        |             |
 |----------------+---------------+----------------+---------+--------+-----------+-----------+-----------+--------+-------------|
 |                |               |                |         | mod    |           |           |           |        |             |
 |----------------+---------------+----------------+---------+--------+-----------+-----------+-----------+--------+-------------|

src/stl/append.rs

@@ -180,6 +180,15 @@ fn reverse_callback(ast: &Seg, _syms: &mut SymTable) -> Result<Ctr, Traceback> {
     }
 }
 
+const ISLIST_DOCSTRING: &str = "takes a single argument, returns true if argument is a list";
+fn islist_callback(ast: &Seg, _syms: &mut SymTable) -> Result<Ctr, Traceback> {
+    if let Ctr::Seg(_) = *ast.car {
+        Ok(Ctr::Bool(true))
+    } else {
+        Ok(Ctr::Bool(false))
+    }
+}
+
 pub fn add_list_lib(syms: &mut SymTable) {
     syms.insert(
         "cons".to_string(),
@@ -264,4 +273,16 @@ pub fn add_list_lib(syms: &mut SymTable) {
             ..Default::default()
         },
     );
+
+    syms.insert(
+        "list?".to_string(),
+        Symbol {
+            name: String::from("list?"),
+            args: Args::Lazy(1),
+            conditional_branches: false,
+            docs: ISLIST_DOCSTRING.to_string(),
+            value: ValueType::Internal(Rc::new(islist_callback)),
+            ..Default::default()
+        },
+    );
 }

tests/test_lib_append.rs

@@ -328,4 +328,38 @@ mod append_lib_tests {
             result.to_string(),
         );
     }
+
+    #[test]
+    fn test_islist_t() {
+        let document = "(list? ())";
+        let result = "true";
+
+        let mut syms = SymTable::new();
+        static_stdlib(&mut syms);
+        dynamic_stdlib(&mut syms, None);
+
+        assert_eq!(
+            *eval(&lex(&document.to_string()).unwrap(), &mut syms)
+                .unwrap()
+                .to_string(),
+            result.to_string(),
+        );
+    }
+
+    #[test]
+    fn test_islist_f() {
+        let document = "(list? 1223)";
+        let result = "false";
+
+        let mut syms = SymTable::new();
+        static_stdlib(&mut syms);
+        dynamic_stdlib(&mut syms, None);
+
+        assert_eq!(
+            *eval(&lex(&document.to_string()).unwrap(), &mut syms)
+                .unwrap()
+                .to_string(),
+            result.to_string(),
+        );
+    }
 }