WIP lambda

* typesystem extended
* docstrings and callback
* tests defined, not implemented

src/segment.rs

@@ -14,6 +14,7 @@
  * You should have received a copy of the GNU General Public License
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
+use crate::sym::UserFn;
 use std::fmt;
 use std::marker::PhantomData;
 use std::ops::{Add, Div, Index, Mul, Sub};
@@ -27,6 +28,7 @@ pub enum Ctr {
     Float(f64),
     Bool(bool),
     Seg(Seg),
+    Lambda(UserFn),
     #[default]
     None,
 }
@@ -40,6 +42,7 @@ pub enum Type {
     Float,
     Bool,
     Seg,
+    Lambda,
     None,
 }
 
@@ -80,6 +83,7 @@ impl Ctr {
             Ctr::Float(_s) => Type::Float,
             Ctr::Bool(_s) => Type::Bool,
             Ctr::Seg(_s) => Type::Seg,
+            Ctr::Lambda(_s) => Type::Lambda,
             Ctr::None => Type::None,
         }
     }
@@ -240,6 +244,7 @@ impl Clone for Ctr {
             Ctr::Float(s) => Ctr::Float(*s),
             Ctr::Bool(s) => Ctr::Bool(*s),
             Ctr::Seg(s) => Ctr::Seg(s.clone()),
+            Ctr::Lambda(s) => Ctr::Seg(s.clone()),
             Ctr::None => Ctr::None,
         }
     }
@@ -260,6 +265,7 @@ impl fmt::Display for Ctr {
                 }
             }
             Ctr::Seg(s) => write!(f, "{}", s),
+            Ctr::Lambda(l) => write!(f, "{}", l),
             Ctr::None => Ok(()),
         }
     }
@@ -398,6 +404,7 @@ impl fmt::Display for Type {
             Type::Float => "float",
             Type::Bool => "bool",
             Type::Seg => "segment",
+            Type::Lambda => "lambda",
             Type::None => "none",
         };
 
@@ -414,6 +421,7 @@ impl std::convert::From<String> for Type {
             "float" => Type::Float,
             "bool" => Type::Bool,
             "segment" => Type::Seg,
+            "lambda" => Type::Lambda,
             _ => Type::None,
         }
     }