diff --git a/crates/file-info/src/ui.rs b/crates/file-info/src/ui.rs
index 4ac6629..158e210 100644
--- a/crates/file-info/src/ui.rs
+++ b/crates/file-info/src/ui.rs
@@ -1,8 +1,8 @@
-use file_parser::{ClassFile, ParseErr};
-use std::error::Error;
+use file_parser::ClassFile;
+use std::io;
 use std::io::Write;
 
-pub fn display_class<W: Write>(mut w: W, class: &ClassFile) -> Result<(), Box<dyn Error>> {
+pub fn display_class<W: Write>(mut w: W, class: &ClassFile) -> Result<(), io::Error> {
     let cp = &class.constant_pool;
 
     writeln!(
@@ -17,24 +17,21 @@ pub fn display_class<W: Write>(mut w: W, class: &ClassFile) -> Result<(), Box<dy
         w,
         "class {} extends {}{} {{",
         &class.this_class.get(cp).name_index.get(cp),
-        match class.super_class.get(cp) {
+        match class.super_class.maybe_get(cp) {
             None => "<none>",
-            Some(class) => &class.name_index.get(cp),
-        }
+            Some(class) => class.name_index.get(cp),
+        },
         if class.interfaces.is_empty() {
             "".to_string()
         } else {
             format!(
                 " implements {}",
-                // this is absolutely terrible but it works i guess
                 class
                     .interfaces
                     .iter()
                     .map(|i| i.get(cp))
-                    .collect::<Result<Vec<_>, ParseErr>>()?
-                    .iter()
                     .map(|i| i.name_index.get(cp))
-                    .collect::<Result<Vec<_>, ParseErr>>()?
+                    .collect::<Vec<_>>()
                     .join(",")
             )
         },
@@ -42,7 +39,7 @@ pub fn display_class<W: Write>(mut w: W, class: &ClassFile) -> Result<(), Box<dy
 
     writeln!(w, " Attributes:")?;
     for attr in &class.attributes {
-        writeln!(w, "  {}", &attr.attribute_name_index.get(cp)?)?;
+        writeln!(w, "  {}", &attr.attribute_name_index.get(cp))?;
     }
     writeln!(w)?;
 
@@ -51,8 +48,8 @@ pub fn display_class<W: Write>(mut w: W, class: &ClassFile) -> Result<(), Box<dy
         writeln!(
             w,
             "  {} {}",
-            &field.descriptor_index.get(cp)?,
-            &field.name_index.get(cp)?
+            &field.descriptor_index.get(cp),
+            &field.name_index.get(cp)
         )?;
     }
     writeln!(w)?;
@@ -62,8 +59,8 @@ pub fn display_class<W: Write>(mut w: W, class: &ClassFile) -> Result<(), Box<dy
         writeln!(
             w,
             "  {} {}",
-            &method.descriptor_index.get(cp)?,
-            &method.name_index.get(cp)?,
+            &method.descriptor_index.get(cp),
+            &method.name_index.get(cp),
         )?;
     }
 
diff --git a/crates/file-parser/src/lib.rs b/crates/file-parser/src/lib.rs
index 722242f..6b7ac86 100644
--- a/crates/file-parser/src/lib.rs
+++ b/crates/file-parser/src/lib.rs
@@ -2,7 +2,7 @@ mod model;
 #[cfg(test)]
 mod test;
 
-use crate::cp_info::FromCpInfo;
+use crate::cp_info::ValidateCpInfo;
 pub use model::*;
 use std::fmt::{Display, Formatter};
 
@@ -46,9 +46,9 @@ impl<'a> Data<'a> {
     }
 
     /// Parses a u2 and validates it in the constant pool
-    fn cp<'pool, T: FromCpInfo<'pool>>(&mut self, pool: &'pool [CpInfo]) -> Result<FromPool<T>> {
+    fn cp<T: ValidateCpInfo>(&mut self, pool: &[CpInfo]) -> Result<FromPool<T>> {
         let index = self.u2()?;
-        let _ = T::try_from_cp_info(pool, index)?;
+        T::validate_cp_info(pool, index)?;
         Ok(index.into())
     }
 
@@ -117,9 +117,12 @@ macro_rules! parse_primitive {
 
 parse_primitive!(u1, u2, u4);
 
-impl<T> Parse for FromPool<T> {
+impl<T> Parse for FromPool<T>
+where
+    T: ValidateCpInfo,
+{
     fn parse(data: &mut Data, cp: &[CpInfo]) -> Result<Self> {
-        Ok(data.u2()?.into())
+        data.cp(cp)
     }
 }
 
@@ -129,7 +132,9 @@ impl Parse for ClassFile {
         assert_eq!(magic, 0xCAFEBABE);
         let minor_version = data.u2()?;
         let major_version = data.u2()?;
+        dbg!("reached constant pool");
         let constant_pool = parse_vec(data.u2()? - 1, data, cp)?; // the minus one is important
+        dbg!("after constant pool");
         let cp = &constant_pool;
         let access_flags = data.u2()?;
         let this_class = data.cp(cp)?;
@@ -160,6 +165,7 @@ impl Parse for ClassFile {
 impl Parse for CpInfo {
     fn parse(data: &mut Data, cp: &[CpInfo]) -> Result<Self> {
         let tag = data.u1()?;
+        dbg!(tag);
 
         Ok(match tag {
             7 => Self {
@@ -302,7 +308,7 @@ impl Parse for AttributeInfo {
 }
 
 impl Parse for AttributeCodeException {
-    fn parse(data: &mut Data, cp: &[CpInfo]) -> Result<Self> {
+    fn parse(data: &mut Data, _cp: &[CpInfo]) -> Result<Self> {
         Ok(Self {
             start_pc: data.last_u2()?,
             end_pc: data.last_u2()?,
@@ -357,7 +363,7 @@ impl Parse for StackMapFrame {
 }
 
 impl Parse for VerificationTypeInfo {
-    fn parse(data: &mut Data, cp: &[CpInfo]) -> Result<Self> {
+    fn parse(data: &mut Data, _cp: &[CpInfo]) -> Result<Self> {
         let tag = data.u1()?;
         Ok(match tag {
             0 => Self::Top { tag },
@@ -397,7 +403,7 @@ impl Parse for AttributeInnerClass {
 }
 
 impl Parse for AttributeLineNumber {
-    fn parse(data: &mut Data, cp: &[CpInfo]) -> Result<Self> {
+    fn parse(data: &mut Data, _cp: &[CpInfo]) -> Result<Self> {
         Ok(Self {
             start_pc: data.u2()?,
             line_number: data.u2()?,
diff --git a/crates/file-parser/src/model/cp_info.rs b/crates/file-parser/src/model/cp_info.rs
index 53aa005..101dd03 100644
--- a/crates/file-parser/src/model/cp_info.rs
+++ b/crates/file-parser/src/model/cp_info.rs
@@ -1,5 +1,5 @@
-use super::*;
-use crate::ParseErr;
+use crate::{u1, u2, u4, CpInfo, CpInfoInner, ParseErr};
+use std::marker::PhantomData;
 
 ///
 /// An index into the constant pool of the class
@@ -18,6 +18,7 @@ pub struct FromPool<T> {
 impl<T: Clone> Copy for FromPool<T> {}
 
 impl<T> From<u2> for FromPool<T> {
+    #[inline]
     fn from(n: u2) -> Self {
         Self {
             inner: n,
@@ -39,7 +40,7 @@ where
 {
     #[inline]
     pub fn get(&self, pool: &'pool [CpInfo]) -> T::Target {
-        T::from_cp_info(&pool[self.inner as usize - 1])
+        T::from_cp_info_with_index(pool, self.inner)
     }
 }
 
@@ -52,15 +53,56 @@ where
         if self.inner == 0 {
             None
         } else {
-            Some(T::from_cp_info(&pool[self.inner as usize - 1]))
+            Some(T::from_cp_info_with_index(pool, self.inner))
         }
     }
 }
 
-pub trait FromCpInfo<'pool> {
+pub trait ValidateCpInfo {
+    /// check that the constant pool entry has the correct type
+    /// `index` is the original, non-null index (it can be 0 optional constants)
+    fn validate_cp_info(info: &[CpInfo], index: u2) -> Result<(), ParseErr>;
+}
+
+pub trait FromCpInfo<'pool>: ValidateCpInfo {
     type Target;
     fn from_cp_info(info: &'pool CpInfo) -> Self::Target;
-    fn try_from_cp_info(info: &'pool [CpInfo], index: u2) -> Result<Self::Target, ParseErr>;
+    fn from_cp_info_with_index(info: &'pool [CpInfo], index: u2) -> Self::Target {
+        Self::from_cp_info(&info[index as usize - 1])
+    }
+}
+
+impl<'pool, T> FromCpInfo<'pool> for Option<T>
+where
+    T: FromCpInfo<'pool>,
+{
+    type Target = Option<T::Target>;
+
+    #[inline]
+    fn from_cp_info(_info: &'pool CpInfo) -> Self::Target {
+        unreachable!("FromPool<Option<T>> should always be get through `from_cp_info_with_index`")
+    }
+
+    fn from_cp_info_with_index(info: &'pool [CpInfo], index: u2) -> Self::Target {
+        if index == 0 {
+            None
+        } else {
+            Some(T::from_cp_info_with_index(info, index))
+        }
+    }
+}
+
+impl<T> ValidateCpInfo for Option<T>
+where
+    T: ValidateCpInfo,
+{
+    fn validate_cp_info(info: &[CpInfo], index: u2) -> Result<(), ParseErr> {
+        if index == 0 {
+            Ok(())
+        } else {
+            T::validate_cp_info(info, index)
+        }
+    }
 }
 
 macro_rules! impl_try_from_cp {
@@ -76,14 +118,20 @@ macro_rules! impl_try_from_cp {
                         _kind => unreachable!(),
                     }
                 }
+            }
 
-                #[inline]
-                fn try_from_cp_info(info: &'pool [CpInfo], index: u2) -> Result<Self::Target, ParseErr> {
+            impl ValidateCpInfo for $name {
+                fn validate_cp_info(info: &[CpInfo], index: u2) -> Result<(), ParseErr> {
                     if index == 0 {
                         return Err(ParseErr("Index must not be 0".to_string()));
                     }
+                    // todo this here might actually be an empty constant pool depending on whether is is still parsing the constant pool
+                    // it needs to be checked after testing
+                    // not now
+                    // pls
+                    // i hate this
                     match &info[index as usize - 1].inner {
-                        CpInfoInner::$name(class) => Ok(class),
+                        CpInfoInner::$name(_) => Ok(()),
                         kind => Err(ParseErr(format!(
                             concat!("Expected '", stringify!($name), "', found '{:?}'"),
                             kind
@@ -95,40 +143,54 @@ macro_rules! impl_try_from_cp {
     };
 }
 
+impl<'pool> FromCpInfo<'pool> for CpInfoInner {
+    type Target = &'pool Self;
+
+    fn from_cp_info(info: &'pool CpInfo) -> Self::Target {
+        &info.inner
+    }
+}
+
+impl ValidateCpInfo for CpInfoInner {
+    fn validate_cp_info(_info: &[CpInfo], _index: u2) -> Result<(), ParseErr> {
+        Ok(())
+    }
+}
+
 #[derive(Debug, Copy, Clone, Hash, PartialEq, Eq)]
 pub struct Class {
     /// Entry must be `Utf8`
-    pub name_index: FromPool<cp_info::Utf8>,
+    pub name_index: FromPool<Utf8>,
 }
 
 #[derive(Debug, Copy, Clone, Hash, PartialEq, Eq)]
 pub struct Fieldref {
     /// May be a class or interface type
-    pub class_index: FromPool<cp_info::Class>,
+    pub class_index: FromPool<Class>,
     /// Entry must be `NameAndType`
-    pub name_and_type_index: FromPool<cp_info::NameAndType>,
+    pub name_and_type_index: FromPool<NameAndType>,
 }
 
 #[derive(Debug, Clone, Hash, PartialEq, Eq)]
 pub struct MethodRef {
     /// Must be a class type
-    pub class_index: FromPool<cp_info::Class>,
+    pub class_index: FromPool<Class>,
     /// Entry must be `NameAndType`
-    pub name_and_type_index: FromPool<cp_info::NameAndType>,
+    pub name_and_type_index: FromPool<NameAndType>,
 }
 
 #[derive(Debug, Copy, Clone, Hash, PartialEq, Eq)]
 pub struct InterfaceMethodref {
     /// Must be an interface type
-    pub class_index: FromPool<cp_info::Class>,
+    pub class_index: FromPool<Class>,
     /// Entry must be `NameAndType`
-    pub name_and_type_index: FromPool<cp_info::NameAndType>,
+    pub name_and_type_index: FromPool<NameAndType>,
 }
 
 #[derive(Debug, Copy, Clone, Hash, PartialEq, Eq)]
 pub struct String {
     /// Entry must be `Utf8`
-    pub string_index: FromPool<cp_info::Utf8>,
+    pub string_index: FromPool<Utf8>,
 }
 
 #[derive(Debug, Copy, Clone, Hash, PartialEq, Eq)]
@@ -165,9 +227,9 @@ pub struct Double {
 #[derive(Debug, Copy, Clone, Hash, PartialEq, Eq)]
 pub struct NameAndType {
     /// Entry must be `Utf8`
-    pub name_index: FromPool<cp_info::Utf8>,
+    pub name_index: FromPool<Utf8>,
     /// Entry must be `Utf8`
-    pub descriptor_index: FromPool<cp_info::Utf8>,
+    pub descriptor_index: FromPool<Utf8>,
 }
 
 #[derive(Debug, Clone, Hash, PartialEq, Eq)]
@@ -187,15 +249,15 @@ pub struct MethodHandle {
 
 #[derive(Debug, Copy, Clone, Hash, PartialEq, Eq)]
 pub enum MethodHandleIndex {
-    Field(FromPool<cp_info::Fieldref>),
-    Method(FromPool<cp_info::MethodInfo>),
-    Interface(FromPool<cp_info::InterfaceMethodref>),
+    Field(FromPool<Fieldref>),
+    Method(FromPool<MethodRef>),
+    Interface(FromPool<InterfaceMethodref>),
 }
 
 #[derive(Debug, Copy, Clone, Hash, PartialEq, Eq)]
 pub struct MethodType {
     /// Entry must be `Utf8`
-    pub descriptor_index: FromPool<cp_info::Utf8>,
+    pub descriptor_index: FromPool<Utf8>,
 }
 
 #[derive(Debug, Copy, Clone, Hash, PartialEq, Eq)]
@@ -203,7 +265,7 @@ pub struct InvokeDynamic {
     /// Must be a valid index into the `bootstrap_methods` array of the bootstrap method table of this class field
     pub bootstrap_method_attr_index: u2,
     /// Entry must `NameAndType`
-    pub name_and_type_index: FromPool<cp_info::NameAndType>,
+    pub name_and_type_index: FromPool<NameAndType>,
 }
 
 // default implementations
@@ -224,6 +286,21 @@ impl_try_from_cp!(
     InvokeDynamic
 );
 
+impl ValidateCpInfo for Utf8 {
+    fn validate_cp_info(info: &[CpInfo], index: u2) -> Result<(), ParseErr> {
+        if index == 0 {
+            return Err(ParseErr("Index must not be 0".to_string()));
+        }
+        match &info[index as usize - 1].inner {
+            CpInfoInner::Utf8(_) => Ok(()),
+            kind => Err(ParseErr(format!(
+                concat!("Expected '", stringify!($name), "', found '{:?}'"),
+                kind
+            ))),
+        }
+    }
+}
+
 // custom implementations
 impl<'pool> FromCpInfo<'pool> for Utf8 {
     type Target = &'pool str;
@@ -235,18 +312,4 @@ impl<'pool> FromCpInfo<'pool> for Utf8 {
             _ => unreachable!(),
         }
     }
-
-    #[inline]
-    fn try_from_cp_info(info: &'pool [CpInfo], index: u2) -> Result<Self::Target, ParseErr> {
-        if index == 0 {
-            return Err(ParseErr("Index must not be 0".to_string()));
-        }
-        match &info[index as usize - 1].inner {
-            CpInfoInner::Utf8(class) => Ok(&class.bytes),
-            kind => Err(ParseErr(format!(
-                concat!("Expected '", stringify!($name), "', found '{:?}'"),
-                kind
-            ))),
-        }
-    }
 }
diff --git a/crates/file-parser/src/model/mod.rs b/crates/file-parser/src/model/mod.rs
index 3b5148e..73b3c7d 100644
--- a/crates/file-parser/src/model/mod.rs
+++ b/crates/file-parser/src/model/mod.rs
@@ -4,8 +4,6 @@
 //! [The .class specs](https://docs.oracle.com/javase/specs/jvms/se7/html/jvms-4.html)
 #![allow(dead_code)]
 
-use std::marker::PhantomData;
-
 /// All of the Constants in the Constant Pool
 pub mod cp_info;
 
@@ -118,15 +116,6 @@ pub struct AttributeInfo {
     pub inner: AttributeInfoInner,
 }
 
-#[derive(Debug, Copy, Clone, Hash, PartialEq, Eq)]
-pub enum ConstantValueIndex {
-    Long(cp_info::Long),
-    Float(cp_info::Float),
-    Double(cp_info::Double),
-    Integer(cp_info::Integer),
-    String(cp_info::String),
-}
-
 /// The Attributes, without the two common fields
 #[derive(Debug, Clone, Hash, PartialEq, Eq)]
 pub enum AttributeInfoInner {
@@ -138,7 +127,7 @@ pub enum AttributeInfoInner {
     /// Only on fields, the constant value of that field
     ConstantValue {
         /// Must be of type `Long`/`Float`/`Double`/`Integer`/`String`
-        constantvalue_index: FromPool<ConstantValueIndex>,
+        constantvalue_index: FromPool<CpInfoInner>,
     },
     /// Only on methods, contains JVM instructions and auxiliary information for a single method
     Code {