diff --git a/lib/interface-types/src/instructions/interpreter.rs b/lib/interface-types/src/instructions/interpreter.rs
index 2859f8069..7da3800f4 100644
--- a/lib/interface-types/src/instructions/interpreter.rs
+++ b/lib/interface-types/src/instructions/interpreter.rs
@@ -2,35 +2,43 @@ use crate::instructions::{
     stack::{Stack, Stackable},
     wasm, Instruction,
 };
-use std::convert::TryFrom;
+use std::{
+    convert::{TryFrom, TryInto},
+    marker::PhantomData,
+};
 
-struct Runtime<'invocation, 'instance, Instance>
+struct Runtime<'invocation, 'instance, Instance, Export>
 where
-    Instance: wasm::Instance,
+    Export: wasm::Export + 'instance,
+    Instance: wasm::Instance<Export> + 'instance,
 {
     invocation_inputs: &'invocation Vec<u64>,
     stack: Stack<u64>,
     wasm_instance: &'instance Instance,
+    wasm_exports: PhantomData<Export>,
 }
 
-pub(crate) struct Interpreter<Instance>
+pub struct Interpreter<Instance, Export>
 where
-    Instance: wasm::Instance,
+    Export: wasm::Export,
+    Instance: wasm::Instance<Export>,
 {
-    executable_instructions: Vec<Box<dyn Fn(&mut Runtime<Instance>) -> Result<(), String>>>,
+    executable_instructions: Vec<Box<dyn Fn(&mut Runtime<Instance, Export>) -> Result<(), String>>>,
 }
 
-impl<Instance> Interpreter<Instance>
+impl<Instance, Export> Interpreter<Instance, Export>
 where
-    Instance: wasm::Instance,
+    Export: wasm::Export,
+    Instance: wasm::Instance<Export>,
 {
     fn iter(
         &self,
-    ) -> impl Iterator<Item = &Box<dyn Fn(&mut Runtime<Instance>) -> Result<(), String>>> + '_ {
+    ) -> impl Iterator<Item = &Box<dyn Fn(&mut Runtime<Instance, Export>) -> Result<(), String>>> + '_
+    {
         self.executable_instructions.iter()
     }
 
-    pub(crate) fn run(
+    pub fn run(
         &self,
         invocation_inputs: &Vec<u64>,
         wasm_instance: &Instance,
@@ -39,6 +47,7 @@ where
             invocation_inputs,
             stack: Stack::new(),
             wasm_instance,
+            wasm_exports: PhantomData,
         };
 
         for executable_instruction in self.iter() {
@@ -52,9 +61,11 @@ where
     }
 }
 
-impl<'binary_input, Instance> TryFrom<&Vec<Instruction<'binary_input>>> for Interpreter<Instance>
+impl<'binary_input, Instance, Export> TryFrom<&Vec<Instruction<'binary_input>>>
+    for Interpreter<Instance, Export>
 where
-    Instance: wasm::Instance,
+    Export: wasm::Export,
+    Instance: wasm::Instance<Export>,
 {
     type Error = String;
 
@@ -62,18 +73,18 @@ where
         let executable_instructions = instructions
             .iter()
             .map(
-                |instruction| -> Box<dyn Fn(&mut Runtime<Instance>) -> Result<(), String>> {
+                |instruction| -> Box<dyn Fn(&mut Runtime<Instance, Export>) -> Result<(), String>> {
                     match instruction {
                         Instruction::ArgumentGet(index) => {
                             let index = index.to_owned();
                             let instruction_name: String = instruction.into();
 
-                            Box::new(move |runtime: &mut Runtime<Instance>| -> Result<(), _> {
+                            Box::new(move |runtime: &mut Runtime<Instance, Export>| -> Result<(), _> {
                                 let invocation_inputs = runtime.invocation_inputs;
 
                                 if index >= (invocation_inputs.len() as u64) {
                                     return Err(format!(
-                                        "`{}` cannot access argument #{} because it does't exist.",
+                                        "`{}` cannot access argument #{} because it doesn't exist.",
                                         instruction_name, index
                                     ));
                                 }
@@ -85,15 +96,51 @@ where
                         }
                         Instruction::CallExport(export_name) => {
                             let export_name = (*export_name).to_owned();
+                            let instruction_name: String = instruction.into();
 
-                            Box::new(move |_runtime: &mut Runtime<Instance>| -> Result<(), _> {
-                                println!("call export {}", export_name);
+                            Box::new(move |runtime: &mut Runtime<Instance, Export>| -> Result<(), _> {
+                                let instance = runtime.wasm_instance;
 
-                                Ok(())
+                                match instance.export(&export_name) {
+                                    Some(export) => {
+                                        let inputs_cardinality = export.inputs_cardinality();
+
+                                        match runtime.stack.pop(inputs_cardinality) {
+                                            Some(inputs) =>  {
+                                                let inputs: Vec<wasm::Value> = inputs.iter().map(|i| wasm::Value::I32(*i as i32)).collect();
+
+                                                match export.call(&inputs) {
+                                                    Ok(outputs) => {
+                                                        for output in outputs.iter() {
+                                                            let output: i32 = output.try_into().unwrap();
+
+                                                            runtime.stack.push(output as u64);
+                                                        }
+
+                                                        Ok(())
+                                                    },
+                                                    Err(_) => Err("failed".into()),
+                                                }
+                                            }
+                                            None => Err(format!(
+                                                "`{}` cannot call the exported function `{}` because there is no enought data in the stack for the arguments (need {}).",
+                                                instruction_name,
+                                                export_name,
+                                                inputs_cardinality,
+                                            ))
+                                        }
+                                    },
+
+                                    None => Err(format!(
+                                        "`{}` cannot call the exported function `{}` because it doesn't exist.",
+                                        instruction_name,
+                                        export_name,
+                                    ))
+                                }
                             })
                         }
                         Instruction::ReadUtf8 => {
-                            Box::new(|_runtime: &mut Runtime<Instance>| -> Result<(), _> {
+                            Box::new(|_runtime: &mut Runtime<Instance, Export>| -> Result<(), _> {
                                 println!("read utf8");
 
                                 Ok(())
@@ -102,7 +149,7 @@ where
                         Instruction::Call(index) => {
                             let index = index.to_owned();
 
-                            Box::new(move |_runtime: &mut Runtime<Instance>| -> Result<(), _> {
+                            Box::new(move |_runtime: &mut Runtime<Instance, Export>| -> Result<(), _> {
                                 println!("call {}", index);
 
                                 Ok(())
@@ -126,8 +173,36 @@ mod tests {
     use crate::instructions::{stack::Stackable, wasm, Instruction};
     use std::{collections::HashMap, convert::TryInto};
 
+    struct Export {
+        inputs: Vec<wasm::Type>,
+        outputs: Vec<wasm::Type>,
+        function: fn(arguments: &[wasm::Value]) -> Result<Vec<wasm::Value>, ()>,
+    }
+
+    impl wasm::Export for Export {
+        fn inputs_cardinality(&self) -> usize {
+            self.inputs.len() as usize
+        }
+
+        fn outputs_cardinality(&self) -> usize {
+            self.outputs.len()
+        }
+
+        fn inputs(&self) -> &[wasm::Type] {
+            &self.inputs
+        }
+
+        fn outputs(&self) -> &[wasm::Type] {
+            &self.outputs
+        }
+
+        fn call(&self, arguments: &[wasm::Value]) -> Result<Vec<wasm::Value>, ()> {
+            (self.function)(arguments)
+        }
+    }
+
     struct Instance {
-        exports: HashMap<String, ()>,
+        exports: HashMap<String, Export>,
     }
 
     impl Instance {
@@ -135,7 +210,19 @@ mod tests {
             Self {
                 exports: {
                     let mut hashmap = HashMap::new();
-                    hashmap.insert("foo".into(), ());
+                    hashmap.insert(
+                        "sum".into(),
+                        Export {
+                            inputs: vec![wasm::Type::I32, wasm::Type::I32],
+                            outputs: vec![wasm::Type::I32],
+                            function: |arguments: &[wasm::Value]| {
+                                let a: i32 = (&arguments[0]).try_into().unwrap();
+                                let b: i32 = (&arguments[1]).try_into().unwrap();
+
+                                Ok(vec![wasm::Value::I32(a + b)])
+                            },
+                        },
+                    );
 
                     hashmap
                 },
@@ -143,9 +230,9 @@ mod tests {
         }
     }
 
-    impl wasm::Instance for Instance {
-        fn export_exists(&self, export_name: &str) -> bool {
-            self.exports.contains_key(export_name)
+    impl wasm::Instance<Export> for Instance {
+        fn export(&self, export_name: &str) -> Option<&Export> {
+            self.exports.get(export_name)
         }
     }
 
@@ -158,15 +245,16 @@ mod tests {
             Instruction::ReadUtf8,
             Instruction::Call(7),
         ];
-        let interpreter: Interpreter<()> = (&instructions).try_into().unwrap();
+        let interpreter: Interpreter<(), ()> = (&instructions).try_into().unwrap();
 
         assert_eq!(interpreter.executable_instructions.len(), 5);
     }
 
     #[test]
     fn test_interpreter_argument_get() {
-        let interpreter: Interpreter<Instance> =
+        let interpreter: Interpreter<Instance, Export> =
             (&vec![Instruction::ArgumentGet(0)]).try_into().unwrap();
+
         let invocation_inputs = vec![42];
         let instance = Instance::new();
         let run = interpreter.run(&invocation_inputs, &instance);
@@ -180,8 +268,9 @@ mod tests {
 
     #[test]
     fn test_interpreter_argument_get_invalid_index() {
-        let interpreter: Interpreter<Instance> =
+        let interpreter: Interpreter<Instance, Export> =
             (&vec![Instruction::ArgumentGet(1)]).try_into().unwrap();
+
         let invocation_inputs = vec![42];
         let instance = Instance::new();
         let run = interpreter.run(&invocation_inputs, &instance);
@@ -192,16 +281,17 @@ mod tests {
 
         assert_eq!(
             error,
-            String::from("`arg.get 1` cannot access argument #1 because it does't exist.")
+            String::from("`arg.get 1` cannot access argument #1 because it doesn't exist.")
         );
     }
 
     #[test]
     fn test_interpreter_argument_get_argument_get() {
-        let interpreter: Interpreter<Instance> =
+        let interpreter: Interpreter<Instance, Export> =
             (&vec![Instruction::ArgumentGet(0), Instruction::ArgumentGet(1)])
                 .try_into()
                 .unwrap();
+
         let invocation_inputs = vec![7, 42];
         let instance = Instance::new();
         let run = interpreter.run(&invocation_inputs, &instance);
@@ -213,20 +303,43 @@ mod tests {
         assert_eq!(stack.as_slice(), &[7, 42]);
     }
 
-    /*
     #[test]
     fn test_interpreter_call_export() {
-        let interpreter: Interpreter<Instance> =
-            (&vec![Instruction::ArgumentGet(7), Instruction::ArgumentGet(42)])
-                .try_into()
-                .unwrap();
-        let run = interpreter.run(&Instance::new());
+        let interpreter: Interpreter<Instance, Export> = (&vec![
+            Instruction::ArgumentGet(1),
+            Instruction::ArgumentGet(0),
+            Instruction::CallExport("sum"),
+        ])
+            .try_into()
+            .unwrap();
+
+        let invocation_inputs = vec![3, 4];
+        let instance = Instance::new();
+        let run = interpreter.run(&invocation_inputs, &instance);
 
         assert!(run.is_ok());
 
         let stack = run.unwrap();
 
-        assert_eq!(stack.as_slice(), &[]);
+        assert_eq!(stack.as_slice(), &[7]);
+    }
+
+    #[test]
+    fn test_interpreter_call_export_invalid_export_name() {
+        let interpreter: Interpreter<Instance, Export> =
+            (&vec![Instruction::CallExport("bar")]).try_into().unwrap();
+
+        let invocation_inputs = vec![];
+        let instance = Instance::new();
+        let run = interpreter.run(&invocation_inputs, &instance);
+
+        assert!(run.is_err());
+
+        let error = run.unwrap_err();
+
+        assert_eq!(
+            error,
+            String::from(r#"`call-export "bar"` cannot call the exported function `bar` because it doesn't exist."#)
+        );
     }
-    */
 }
diff --git a/lib/interface-types/src/instructions/stack.rs b/lib/interface-types/src/instructions/stack.rs
index c9b42d6ad..1d139a77c 100644
--- a/lib/interface-types/src/instructions/stack.rs
+++ b/lib/interface-types/src/instructions/stack.rs
@@ -1,4 +1,4 @@
-pub(crate) trait Stackable {
+pub trait Stackable {
     type Item;
 
     fn is_empty(&self) -> bool;
@@ -9,7 +9,7 @@ pub(crate) trait Stackable {
 }
 
 #[derive(Debug)]
-pub(crate) struct Stack<T> {
+pub struct Stack<T> {
     inner: Vec<T>,
 }
 
diff --git a/lib/interface-types/src/instructions/wasm.rs b/lib/interface-types/src/instructions/wasm.rs
new file mode 100644
index 000000000..382fe17bc
--- /dev/null
+++ b/lib/interface-types/src/instructions/wasm.rs
@@ -0,0 +1,91 @@
+use std::convert::TryFrom;
+
+pub enum Type {
+    I32,
+    I64,
+    F32,
+    F64,
+    V128,
+}
+
+#[derive(Debug)]
+pub enum Value {
+    I32(i32),
+    I64(i64),
+    F32(f32),
+    F64(f64),
+    V128(u128),
+}
+
+macro_rules! from_x_for_value {
+    ($native_type:ty, $value_variant:ident) => {
+        impl From<$native_type> for Value {
+            fn from(n: $native_type) -> Self {
+                Self::$value_variant(n)
+            }
+        }
+
+        impl TryFrom<&Value> for $native_type {
+            type Error = &'static str;
+
+            fn try_from(w: &Value) -> Result<Self, Self::Error> {
+                match *w {
+                    Value::$value_variant(n) => Ok(n),
+                    _ => Err("Invalid cast."),
+                }
+            }
+        }
+    };
+}
+
+from_x_for_value!(i32, I32);
+from_x_for_value!(i64, I64);
+from_x_for_value!(f32, F32);
+from_x_for_value!(f64, F64);
+from_x_for_value!(u128, V128);
+
+pub trait Export {
+    fn inputs_cardinality(&self) -> usize;
+    fn outputs_cardinality(&self) -> usize;
+    fn inputs(&self) -> &[Type];
+    fn outputs(&self) -> &[Type];
+    fn call(&self, arguments: &[Value]) -> Result<Vec<Value>, ()>;
+}
+
+pub trait Instance<E>
+where
+    E: Export,
+{
+    fn export(&self, export_name: &str) -> Option<&E>;
+}
+
+impl Export for () {
+    fn inputs_cardinality(&self) -> usize {
+        0
+    }
+
+    fn outputs_cardinality(&self) -> usize {
+        0
+    }
+
+    fn inputs(&self) -> &[Type] {
+        &[]
+    }
+
+    fn outputs(&self) -> &[Type] {
+        &[]
+    }
+
+    fn call(&self, _arguments: &[Value]) -> Result<Vec<Value>, ()> {
+        Err(())
+    }
+}
+
+impl<E> Instance<E> for ()
+where
+    E: Export,
+{
+    fn export(&self, _export_name: &str) -> Option<&E> {
+        None
+    }
+}