feat: vector concatenation

3 files changed, 23 insertions, 0 deletions

diff --git a/src/sexp/display.rs b/src/sexp/display.rs
index e2f4ffc..ec1b421 100644
--- a/src/sexp/display.rs
+++ b/src/sexp/display.rs
@@ -28,6 +28,7 @@ impl fmt::Display for SLeaf {
 	    RestPat(s) => format!("..{s}"),
             Quote  => "quote".to_string(),
             Vector => "vector".to_string(),
+            Concat => "<>".to_string(),
 	    Print  => "print".to_string(),
             Let    => "let".to_string(),
 	    Fun    => "fn".to_string(),
diff --git a/src/sexp/mod.rs b/src/sexp/mod.rs
index aa51811..1a90f52 100644
--- a/src/sexp/mod.rs
+++ b/src/sexp/mod.rs
@@ -30,6 +30,7 @@ pub enum SLeaf {
     Or,
     Not,
     Xor,
+    Concat,
 
     Quote,
     Vector,
diff --git a/src/sexp/step.rs b/src/sexp/step.rs
index 9077401..59b201c 100644
--- a/src/sexp/step.rs
+++ b/src/sexp/step.rs
@@ -441,6 +441,27 @@ impl SExp {
 	    },
 
 
+	    // Concatenation
+	    SCons(op, l) if *op == Atom(Concat) => {
+		let ls = l.parts();
+		let firstvec = ls.get(0).unwrap();
+		let secondvec = ls.get(1).unwrap();
+		let firstvec = match firstvec {
+		    SCons(a, b) if **a == Atom(Vector) => *b.clone(),
+		    t => t.clone(),
+		};
+		let secondvec = match secondvec {
+		    SCons(a, b) if **a == Atom(Vector) => *b.clone(),
+		    t => t.clone(),
+		};
+		let mut res = Atom(Nil);
+		for exp in firstvec.parts().into_iter().chain(secondvec.parts()).rev() {
+		    res = scons(exp, res);
+		}
+		Ok(scons(Vector, res))
+	    },
+
+
             // Arithmetic