diff --git a/maaru/src/lib.rs b/maaru/src/lib.rs
index 75192fb..c04adcc 100644
--- a/maaru/src/lib.rs
+++ b/maaru/src/lib.rs
@@ -7,7 +7,7 @@ mod parser;
 mod eval;
 mod compilation;
 
-use schala_repl::{ProgrammingLanguageInterface, EvalOptions, LanguageOutput, TraceArtifact};
+use schala_repl::{ProgrammingLanguageInterface, EvalOptions, UnfinishedComputation, FinishedComputation, TraceArtifact};
 
 #[derive(Debug)]
 pub struct TokenError {
@@ -42,8 +42,8 @@ impl<'a> ProgrammingLanguageInterface for Maaru<'a> {
     format!("maaru")
   }
 
-  fn evaluate_in_repl(&mut self, input: &str, options: &EvalOptions) -> LanguageOutput {
-    let mut output = LanguageOutput::default();
+  fn execute_pipeline(&mut self, input: &str, options: &EvalOptions) -> FinishedComputation {
+    let mut output = UnfinishedComputation::default();
 
     let tokens = match tokenizer::tokenize(input) {
       Ok(tokens) => {
@@ -53,8 +53,7 @@ impl<'a> ProgrammingLanguageInterface for Maaru<'a> {
         tokens
       },
       Err(err) => {
-        output.add_output(format!("Tokenization error: {:?}\n", err.msg));
-        return output;
+        return output.finish(Err(format!("Tokenization error: {:?}\n", err.msg)))
       }
     };
 
@@ -66,16 +65,14 @@ impl<'a> ProgrammingLanguageInterface for Maaru<'a> {
         ast
       },
       Err(err) => {
-        output.add_output(format!("Parse error: {:?}\n", err.msg));
-        return output;
+        return output.finish(Err(format!("Parse error: {:?}\n", err.msg)))
       }
     };
     let mut evaluation_output = String::new();
     for s in self.evaluator.run(ast).iter() {
       evaluation_output.push_str(s);
     }
-    output.add_output(evaluation_output);
-    return output;
+    output.finish(Ok(evaluation_output))
   }
 
   /* TODO make this work with new framework */
diff --git a/robo/src/lib.rs b/robo/src/lib.rs
index af0701b..f6cf2b1 100644
--- a/robo/src/lib.rs
+++ b/robo/src/lib.rs
@@ -4,7 +4,7 @@ extern crate itertools;
 extern crate schala_repl;
 
 use itertools::Itertools;
-use schala_repl::{ProgrammingLanguageInterface, EvalOptions, LanguageOutput};
+use schala_repl::{ProgrammingLanguageInterface, EvalOptions, FinishedComputation, UnfinishedComputation};
 
 pub struct Robo {
 }
@@ -155,18 +155,16 @@ impl ProgrammingLanguageInterface for Robo {
     format!("robo")
   }
 
-  fn evaluate_in_repl(&mut self, input: &str, _eval_options: &EvalOptions) -> LanguageOutput {
-    let mut output = LanguageOutput::default();
+  fn execute_pipeline(&mut self, input: &str, _eval_options: &EvalOptions) -> FinishedComputation {
+    let output = UnfinishedComputation::default();
     let tokens = match tokenize(input) {
       Ok(tokens) => tokens,
       Err(e) => {
-        output.add_output(format!("Tokenize error: {:?}", e));
-        return output;
+        return output.finish(Err(format!("Tokenize error: {:?}", e)));
       }
     };
 
-    output.add_output(format!("{:?}", tokens));
-    output
+    output.finish(Ok(format!("{:?}", tokens)))
   }
 }
 
diff --git a/rukka/src/lib.rs b/rukka/src/lib.rs
index 3736bdf..cf470a5 100644
--- a/rukka/src/lib.rs
+++ b/rukka/src/lib.rs
@@ -4,7 +4,7 @@ extern crate itertools;
 extern crate schala_repl;
 
 use itertools::Itertools;
-use schala_repl::{ProgrammingLanguageInterface, EvalOptions, LanguageOutput};
+use schala_repl::{ProgrammingLanguageInterface, EvalOptions, UnfinishedComputation, FinishedComputation};
 use std::iter::Peekable;
 use std::vec::IntoIter;
 use std::str::Chars;
@@ -73,12 +73,11 @@ impl ProgrammingLanguageInterface for Rukka {
     format!("rukka")
   }
 
-  fn evaluate_in_repl(&mut self, input: &str, _eval_options: &EvalOptions) -> LanguageOutput {
-    let mut output = LanguageOutput::default();
+  fn execute_pipeline(&mut self, input: &str, _eval_options: &EvalOptions) -> FinishedComputation {
+    let mut output = UnfinishedComputation::default();
     let sexps = match read(input) {
       Err(err) => {
-        output.add_output(format!("Error: {}", err));
-        return output;
+        return output.finish(Err(format!("Error: {}", err)));
       },
       Ok(sexps) => sexps
     };
@@ -89,8 +88,7 @@ impl ProgrammingLanguageInterface for Rukka {
         Err(err) => format!("{} Error: {}", i, err),
       }
     }).intersperse(format!("\n")).collect();
-    output.add_output(output_str);
-    output
+    output.finish(Ok(output_str))
   }
 }
 
diff --git a/schala-repl/src/language.rs b/schala-repl/src/language.rs
index e28e7b5..9164450 100644
--- a/schala-repl/src/language.rs
+++ b/schala-repl/src/language.rs
@@ -163,12 +163,6 @@ impl TraceArtifact {
 }
 
 pub trait ProgrammingLanguageInterface {
-  /* old */
-  fn evaluate_in_repl(&mut self, _: &str, _: &EvalOptions) -> LanguageOutput {
-    LanguageOutput { output: format!("Defunct"), artifacts: vec![], failed: false }
-  }
-  /* old */
-
   fn execute_pipeline(&mut self, _input: &str, _eval_options: &EvalOptions) -> FinishedComputation {
     FinishedComputation { artifacts: HashMap::new(), text_output: Err(format!("Execution pipeline not done")) }
   }
diff --git a/schala-repl/src/webapp.rs b/schala-repl/src/webapp.rs
index 5d4975e..b4f01a1 100644
--- a/schala-repl/src/webapp.rs
+++ b/schala-repl/src/webapp.rs
@@ -35,8 +35,8 @@ struct Output {
 fn interpreter_input(input: Json<Input>, generators: State<Vec<PLIGenerator>>) -> Json<Output> {
   let schala_gen = generators.get(0).unwrap();
   let mut schala: Box<ProgrammingLanguageInterface> = schala_gen();
-  let code_output = schala.evaluate_in_repl(&input.source, &EvalOptions::default());
-  Json(Output { text: code_output.to_string() })
+  let code_output = schala.execute_pipeline(&input.source, &EvalOptions::default());
+  Json(Output { text: code_output.to_repl() })
 }
 
 pub fn web_main(language_generators: Vec<PLIGenerator>) {