diff --git a/schala-lang/language/src/ast/mod.rs b/schala-lang/language/src/ast/mod.rs
index 4a06e67..f0883d5 100644
--- a/schala-lang/language/src/ast/mod.rs
+++ b/schala-lang/language/src/ast/mod.rs
@@ -6,7 +6,7 @@ mod walker;
 mod visitor;
 mod visitor_test;
 mod operators;
-pub use operators::*;
+pub use operators::{PrefixOp, BinOp};
 pub use visitor::ASTVisitor;
 pub use walker::walk_ast;
 use crate::tokenizing::Location;
diff --git a/schala-lang/language/src/ast/operators.rs b/schala-lang/language/src/ast/operators.rs
index 0e3f2b0..d02b6c5 100644
--- a/schala-lang/language/src/ast/operators.rs
+++ b/schala-lang/language/src/ast/operators.rs
@@ -1,20 +1,21 @@
 use std::rc::Rc;
-use std::str::FromStr;
 
 use crate::tokenizing::TokenKind;
-use crate::builtin::Builtin;
 
 #[derive(Debug, PartialEq, Clone)]
 pub struct PrefixOp {
   sigil: Rc<String>,
-  pub builtin: Option<Builtin>,
 }
 
 impl PrefixOp {
-  #[allow(dead_code)]
-  pub fn sigil(&self) -> &Rc<String> {
+  pub fn from_sigil(sigil: &str) -> PrefixOp {
+    PrefixOp { sigil: Rc::new(sigil.to_string()) }
+  }
+
+  pub fn sigil(&self) -> &str {
     &self.sigil
   }
+
   pub fn is_prefix(op: &str) -> bool {
     match op {
       "+" => true,
@@ -25,37 +26,20 @@ impl PrefixOp {
   }
 }
 
-impl FromStr for PrefixOp {
-  type Err = ();
-
-  fn from_str(s: &str) -> Result<Self, Self::Err> {
-    use Builtin::*;
-
-    let builtin = match s {
-      "+" => Ok(Increment),
-      "-" => Ok(Negate),
-      "!" => Ok(BooleanNot),
-      _ => Err(())
-    };
-
-    builtin.map(|builtin| PrefixOp { sigil: Rc::new(s.to_string()), builtin: Some(builtin) })
-  }
-}
-
 #[derive(Debug, PartialEq, Clone)]
 pub struct BinOp {
   sigil: Rc<String>,
-  pub builtin: Option<Builtin>,
 }
 
 impl BinOp {
   pub fn from_sigil(sigil: &str) -> BinOp {
-    let builtin = Builtin::from_str(sigil).ok();
-    BinOp { sigil: Rc::new(sigil.to_string()), builtin }
+    BinOp { sigil: Rc::new(sigil.to_string()) }
   }
-  pub fn sigil(&self) -> &Rc<String> {
+
+  pub fn sigil(&self) -> &str {
     &self.sigil
   }
+
   pub fn from_sigil_token(tok: &TokenKind) -> Option<BinOp> {
     let s = token_kind_to_sigil(tok)?;
     Some(BinOp::from_sigil(s))
diff --git a/schala-lang/language/src/builtin.rs b/schala-lang/language/src/builtin.rs
index 09176cd..0d12bda 100644
--- a/schala-lang/language/src/builtin.rs
+++ b/schala-lang/language/src/builtin.rs
@@ -1,7 +1,10 @@
 use std::str::FromStr;
+use std::convert::TryFrom;
 
 use crate::typechecking::{TypeConst, Type};
+use crate::ast::{BinOp, PrefixOp};
 
+/// "Builtin" computational operations with some kind of semantics, mostly mathematical operations.
 #[derive(Debug, Clone, Copy, PartialEq)]
 pub enum Builtin {
   Add,
@@ -66,6 +69,29 @@ impl Builtin {
   }
 }
 
+impl TryFrom<&BinOp> for Builtin {
+  type Error = ();
+
+  fn try_from(binop: &BinOp) -> Result<Self, Self::Error> {
+    FromStr::from_str(binop.sigil())
+  }
+}
+
+impl TryFrom<&PrefixOp> for Builtin {
+  type Error = ();
+
+  fn try_from(prefix_op: &PrefixOp) -> Result<Self, Self::Error> {
+    use Builtin::*;
+
+    match prefix_op.sigil() {
+      "+" => Ok(Increment),
+      "-" => Ok(Negate),
+      "!" => Ok(BooleanNot),
+      _ => Err(())
+    }
+  }
+}
+
 impl FromStr for Builtin {
   type Err = ();
 
diff --git a/schala-lang/language/src/parsing/mod.rs b/schala-lang/language/src/parsing/mod.rs
index 93e7115..aac1534 100644
--- a/schala-lang/language/src/parsing/mod.rs
+++ b/schala-lang/language/src/parsing/mod.rs
@@ -161,7 +161,6 @@
 mod test;
 
 use std::rc::Rc;
-use std::str::FromStr;
 
 use crate::tokenizing::*;
 use crate::tokenizing::Kw::*;
@@ -658,7 +657,7 @@ impl Parser {
           _ => unreachable!(),
         };
         let expr = self.primary()?;
-        let prefix_op = PrefixOp::from_str(sigil.as_str()).unwrap();
+        let prefix_op = PrefixOp::from_sigil(sigil.as_str());
         Ok(Expression::new(
           self.id_store.fresh(),
           ExpressionKind::PrefixExp(prefix_op, Box::new(expr))
diff --git a/schala-lang/language/src/parsing/test.rs b/schala-lang/language/src/parsing/test.rs
index 4575953..9bfdfe4 100644
--- a/schala-lang/language/src/parsing/test.rs
+++ b/schala-lang/language/src/parsing/test.rs
@@ -1,6 +1,5 @@
 #![cfg(test)]
 use std::rc::Rc;
-use std::str::FromStr;
 
 use crate::tokenizing::Location;
 use super::{Parser, ParseResult, tokenize};
@@ -109,7 +108,7 @@ macro_rules! binexp {
   ($op:expr, $lhs:expr, $rhs:expr) => { BinExp(BinOp::from_sigil($op), bx!(Expression::new(ItemIdStore::new_id(), $lhs).into()), bx!(Expression::new(ItemIdStore::new_id(), $rhs).into())) }
 }
 macro_rules! prefexp {
-  ($op:expr, $lhs:expr) => { PrefixExp(PrefixOp::from_str($op).unwrap(), bx!(Expression::new(ItemIdStore::new_id(), $lhs).into())) }
+  ($op:expr, $lhs:expr) => { PrefixExp(PrefixOp::from_sigil($op), bx!(Expression::new(ItemIdStore::new_id(), $lhs).into())) }
 }
 macro_rules! exst {
   ($expr_type:expr) => { make_statement(StatementKind::Expression(Expression::new(ItemIdStore::new_id(), $expr_type).into())) };
diff --git a/schala-lang/language/src/reduced_ast.rs b/schala-lang/language/src/reduced_ast.rs
index 839ef3c..b3a9a6c 100644
--- a/schala-lang/language/src/reduced_ast.rs
+++ b/schala-lang/language/src/reduced_ast.rs
@@ -14,6 +14,7 @@
 //! built from the ReducedAST.
 use std::rc::Rc;
 use std::str::FromStr;
+use std::convert::TryFrom;
 
 use crate::ast::*;
 use crate::symbol_table::{Symbol, SymbolSpec, SymbolTable, FullyQualifiedSymbolName};
@@ -337,7 +338,8 @@ impl<'a> Reducer<'a> {
   }
 
   fn prefix(&mut self, prefix: &PrefixOp, arg: &Box<Expression>) -> Expr {
-    match prefix.builtin {
+    let builtin: Option<Builtin> = TryFrom::try_from(prefix).ok();
+    match builtin {
       Some(op) => {
         let f = Box::new(Expr::Func(Func::BuiltIn(op)));
         Expr::Call { f, args: vec![self.expression(arg)] }
diff --git a/schala-lang/language/src/typechecking.rs b/schala-lang/language/src/typechecking.rs
index 802edbd..3f8fa49 100644
--- a/schala-lang/language/src/typechecking.rs
+++ b/schala-lang/language/src/typechecking.rs
@@ -1,8 +1,10 @@
 use std::rc::Rc;
 use std::fmt::Write;
+use std::convert::TryFrom;
 
 use ena::unify::{UnifyKey, InPlaceUnificationTable, UnificationTable, EqUnifyValue};
 
+use crate::builtin::Builtin;
 use crate::ast::*;
 use crate::util::ScopeStack;
 use crate::util::deref_optional_box;
@@ -332,7 +334,8 @@ impl<'a> TypeContext<'a> {
   }
 
   fn prefix(&mut self, op: &PrefixOp, expr: &Expression) -> InferResult<Type> {
-    let tf = match op.builtin.map(|b| b.get_type()) {
+    let builtin: Option<Builtin> = TryFrom::try_from(op).ok();
+    let tf = match builtin.map(|b| b.get_type()) {
       Some(ty) => ty,
       None => return TypeError::new("no type found")
     };
@@ -342,7 +345,8 @@ impl<'a> TypeContext<'a> {
   }
 
   fn binexp(&mut self, op: &BinOp, lhs: &Expression, rhs: &Expression) -> InferResult<Type> {
-    let tf = match op.builtin.map(|b| b.get_type()) {
+    let builtin: Option<Builtin> = TryFrom::try_from(op).ok();
+    let tf = match builtin.map(|b| b.get_type()) {
       Some(ty) => ty,
       None => return TypeError::new("no type found"),
     };