diff --git a/src/compiler/definitions.rs b/src/compiler/definitions.rs
index 2bf5c29..ffbafad 100644
--- a/src/compiler/definitions.rs
+++ b/src/compiler/definitions.rs
@@ -54,7 +54,7 @@ fn reduce(e: &AstNode, ctx: &mut Scope) -> Result<()> {
                 .kind(match kind {
                     Kind::Atomic => Kind::Atomic,
                     Kind::Phantom => Kind::Phantom,
-                    Kind::Composite(_) => Kind::Phantom,
+                    Kind::Computed(_) => Kind::Phantom,
                 })
                 .and_padding_value(*padding_value)
                 .t(t.m())
diff --git a/src/compiler/generator.rs b/src/compiler/generator.rs
index 91a8999..58cc43d 100644
--- a/src/compiler/generator.rs
+++ b/src/compiler/generator.rs
@@ -473,7 +473,8 @@ impl ConstraintSet {
             {
                 match c {
                     Computation::Interleaved { target, .. }
-                    | Computation::CyclicFrom { target, .. } => {
+                    | Computation::CyclicFrom { target, .. }
+                    | Computation::Composite { target, .. } => {
                         let col = self.columns.column(&target).unwrap();
                         let reg = self.columns.new_register(col.handle.clone(), col.t);
                         self.columns.assign_register(&target, reg).unwrap();
@@ -1511,11 +1512,11 @@ pub fn reduce(e: &AstNode, ctx: &mut Scope, settings: &CompileSettings) -> Resul
             kind: k,
             ..
         } => match k {
-            Kind::Composite(e) => {
+            Kind::Computed(e) => {
                 let n = reduce(e, ctx, settings)?.unwrap();
                 ctx.edit_symbol(name, &|x| {
                     if let Expression::Column { kind, .. } = x {
-                        *kind = Kind::Composite(Box::new(n.clone()))
+                        *kind = Kind::Computed(Box::new(n.clone()))
                     }
                 })?;
                 Ok(None)
diff --git a/src/compiler/mod.rs b/src/compiler/mod.rs
index da5cbdb..f588b1c 100644
--- a/src/compiler/mod.rs
+++ b/src/compiler/mod.rs
@@ -179,7 +179,7 @@ pub fn make<S1: AsRef<str>, S2: AsRef<str>>(
                         let id = columns.insert_column(column)?;
                         match k {
                             Kind::Atomic | Kind::Phantom => (),
-                            Kind::Composite(e) => computations
+                            Kind::Computed(e) => computations
                                 .insert(
                                     &id,
                                     Computation::Composite {
diff --git a/src/compiler/parser.rs b/src/compiler/parser.rs
index de5b355..5e9afdc 100755
--- a/src/compiler/parser.rs
+++ b/src/compiler/parser.rs
@@ -152,14 +152,14 @@ pub enum Kind<T> {
     Phantom,
     /// a composite column is similar to a phantom column, but the expression
     /// computing it is known
-    Composite(Box<T>),
+    Computed(Box<T>),
 }
 impl<T> Kind<T> {
     pub fn to_nil(&self) -> Kind<()> {
         match self {
             Kind::Atomic => Kind::Atomic,
             Kind::Phantom => Kind::Phantom,
-            Kind::Composite(_) => Kind::Composite(Box::new(())),
+            Kind::Computed(_) => Kind::Computed(Box::new(())),
         }
     }
 }
@@ -618,6 +618,7 @@ struct ColumnAttributes {
     range: OnceCell<Domain>,
     padding_value: OnceCell<i64>,
     base: OnceCell<Base>,
+    computation: Option<AstNode>,
 }
 
 impl std::convert::TryInto<DisplayableColumn> for ColumnAttributes {
@@ -731,7 +732,10 @@ fn parse_column_attributes(source: AstNode) -> Result<ColumnAttributes> {
                     })?;
                 ColumnParser::Begin
             }
-            ColumnParser::Computation => todo!(),
+            ColumnParser::Computation => {
+                attributes.computation = Some(x);
+                ColumnParser::Begin
+            }
             ColumnParser::PaddingValue => {
                 attributes.padding_value.set(x.as_i64()?).map_err(|_| {
                     anyhow!(
@@ -808,7 +812,10 @@ fn parse_defcolumns<I: Iterator<Item = Result<AstNode>>>(
                                     .cloned()
                                     .unwrap_or(Magma::native()),
                             ),
-                            kind: Kind::Atomic,
+                            kind: column_attributes
+                                .computation
+                                .map(|c| Kind::Computed(Box::new(c)))
+                                .unwrap_or(Kind::Atomic),
                             padding_value: column_attributes.padding_value.get().cloned(),
                             base,
                         }
diff --git a/src/transformer.rs b/src/transformer.rs
index 2bf7b9c..a4e5204 100644
--- a/src/transformer.rs
+++ b/src/transformer.rs
@@ -140,7 +140,7 @@ fn validate_computation(cs: &mut Vec<Node>, x_expr: &Node, x_col: &Handle) {
                 x_expr.clone(),
                 Node::column()
                     .handle(x_col.to_owned())
-                    .kind(Kind::Composite(Box::new(x_expr.clone())))
+                    .kind(Kind::Computed(Box::new(x_expr.clone())))
                     .t(Magma::native())
                     .build(),
             ])
diff --git a/src/transformer/inverses.rs b/src/transformer/inverses.rs
index 021bab7..e46df57 100644
--- a/src/transformer/inverses.rs
+++ b/src/transformer/inverses.rs
@@ -129,7 +129,7 @@ impl ConstraintSet {
                 let inverted_id = self.columns.insert_column_and_register(
                     Column::builder()
                         .handle(inverted_handle.clone())
-                        .kind(Kind::Composite(Box::new(())))
+                        .kind(Kind::Computed(Box::new(())))
                         .build(),
                 )?;
 
diff --git a/src/transformer/splatter.rs b/src/transformer/splatter.rs
index f65a9b1..a238089 100644
--- a/src/transformer/splatter.rs
+++ b/src/transformer/splatter.rs
@@ -277,7 +277,7 @@ impl ConstraintSet {
                             .handle(new_handle.to_owned())
                             .t(new_magma)
                             .base(Base::Hex)
-                            .kind(Kind::Composite(Box::new(())))
+                            .kind(Kind::Computed(Box::new(())))
                             .build(),
                     )
                     .unwrap();