diff --git a/Cargo.lock b/Cargo.lock
index abb2a7a..ac6a9ae 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1,7 +1,5 @@
 # This file is automatically @generated by Cargo.
 # It is not intended for manual editing.
-version = 3
-
 [[package]]
 name = "atty"
 version = "0.2.14"
@@ -181,6 +179,7 @@ version = "1.1.1"
 dependencies = [
  "criterion",
  "enve_mod",
+ "estring",
  "lazy_static",
 ]
 
@@ -195,6 +194,10 @@ dependencies = [
  "syn",
 ]
 
+[[package]]
+name = "estring"
+version = "0.1.0"
+
 [[package]]
 name = "half"
 version = "1.8.2"
diff --git a/Cargo.toml b/Cargo.toml
index fdd4e78..83d08e4 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -1,6 +1,7 @@
 [workspace]
 members = [
-    "enve_mod",
+  "estring",
+  "enve_mod",
 ]
 
 [package]
@@ -21,13 +22,14 @@ readme = "../README.md"
 
 [features]
 default = []
-number = []
-bool  = []
-vec = []
+number = ["estring/number"]
+bool  = ["estring/bool"]
+vec = ["estring/vec"]
 
 macro = ["enve_mod"]
 
 [dependencies]
+estring = { version = "0", path = "./estring" }
 enve_mod = { version = "1.1", path = "./enve_mod", optional = true }
 
 [dev-dependencies]
diff --git a/LICENSE b/LICENSE
index 96a1a25..6b5ce3d 100644
--- a/LICENSE
+++ b/LICENSE
@@ -1,6 +1,6 @@
 MIT License
 
-Copyright (c) 2019 pleshevskiy
+Copyright (c) 2019-2022 pleshevskiy
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal
diff --git a/estring/Cargo.toml b/estring/Cargo.toml
new file mode 100644
index 0000000..20da45e
--- /dev/null
+++ b/estring/Cargo.toml
@@ -0,0 +1,28 @@
+[package]
+name = "estring"
+description = "A simple way to parse a string using type annotations"
+version = "0.1.0"
+edition = "2018"
+authors = ["Dmitriy Pleshevskiy <dmitriy@ideascup.me>"]
+readme = "README.md"
+repository = "https://github.com/pleshevskiy/itconfig-rs/tree/redesign/estring"
+license = "MIT"
+keywords = ["parsing", "type", "annotations", "customizable"]
+categories = ["data-structures", "parsing"]
+
+# rust-version = "1.51.0" # The first version of Cargo that supports this field is 1.56.0
+
+[metadata]
+msrv = "1.51.0"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[features]
+number = []
+bool = []
+vec = []
+
+[dependencies]
+
+[badges]
+maintenance = { status = "actively-developed" }
diff --git a/estring/LICENSE b/estring/LICENSE
new file mode 100644
index 0000000..8afbf27
--- /dev/null
+++ b/estring/LICENSE
@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2022 pleshevskiy
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.
diff --git a/estring/README.md b/estring/README.md
new file mode 100644
index 0000000..b49dbaa
--- /dev/null
+++ b/estring/README.md
@@ -0,0 +1,57 @@
+# EString
+
+A simple way to parse a string using type annotations.
+
+This package was originally designed for [enve]
+
+[enve]: https://github.com/pleshevskiy/itconfig-rs/tree/redesign
+
+## Getting started
+
+```rust
+use estring::{SepVec, EString};
+
+type PlusVec<T> = SepVec<T, '+'>;
+type MulVec<T> = SepVec<T, '*'>;
+
+fn main() -> Result<(), estring::ParseError> {
+    let res = EString::from("10+5*2+3")
+        .parse::<PlusVec<MulVec<f32>>>()?
+        .iter()
+        .map(|m| m.iter().product::<f32>())
+        .sum::<f32>();
+
+    assert_eq!(res, 23.0);
+    Ok(())
+}
+```
+
+You can use custom types as annotations! Just implement `TryFrom<EString>`!
+
+## Installation
+
+**The MSRV is 1.51.0**
+
+Add `estring = { version = "0.1", features = ["vec", "number"] }` as a
+dependency in `Cargo.toml`.
+
+`Cargo.toml` example:
+
+```toml
+[package]
+name = "my-crate"
+version = "0.1.0"
+authors = ["Me <user@rust-lang.org>"]
+
+[dependencies]
+estring = { version = "0.1", features = ["vec", "number"] }
+```
+
+## License
+
+**MIT**. See [LICENSE](./LICENSE) to see the full text.
+
+## Contributors
+
+[pleshevskiy](https://github.com/pleshevskiy) (Dmitriy Pleshevskiy) – creator,
+maintainer.
diff --git a/estring/src/core.rs b/estring/src/core.rs
new file mode 100644
index 0000000..68a2151
--- /dev/null
+++ b/estring/src/core.rs
@@ -0,0 +1,99 @@
+//! Contains the ``EString`` type, as well as the basic implementation of conversions to
+//! string types
+//!
+#[cfg(any(feature = "number", feature = "bool"))]
+pub mod prim;
+#[cfg(any(feature = "number", feature = "bool"))]
+pub use prim::*;
+
+#[cfg(feature = "vec")]
+pub mod vec;
+#[cfg(feature = "vec")]
+pub use vec::*;
+
+use crate::ParseError;
+use std::convert::{Infallible, TryFrom};
+
+/// Wrapper under String type.
+#[derive(Debug, Default, PartialEq, Eq, Clone)]
+pub struct EString(pub String);
+
+impl EString {
+    /// Parses inner string by type annotations and returns result.
+    ///
+    /// # Errors
+    ///
+    /// Will return `Err` if estring cannot parse inner fragment
+    ///
+    #[inline]
+    pub fn parse<T: TryFrom<EString>>(self) -> Result<T, ParseError> {
+        let orig = self.0.clone();
+        <T as TryFrom<EString>>::try_from(self).map_err(|_| ParseError(orig))
+    }
+}
+
+impl<T> From<T> for EString
+where
+    T: std::fmt::Display,
+{
+    #[inline]
+    fn from(val: T) -> Self {
+        Self(val.to_string())
+    }
+}
+
+impl std::ops::Deref for EString {
+    type Target = String;
+
+    #[inline]
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+impl TryFrom<EString> for String {
+    type Error = Infallible;
+
+    #[inline]
+    fn try_from(s: EString) -> Result<Self, Self::Error> {
+        Ok(s.0)
+    }
+}
+
+impl TryFrom<EString> for &'static str {
+    type Error = Infallible;
+
+    #[inline]
+    fn try_from(s: EString) -> Result<Self, Self::Error> {
+        Ok(Box::leak(s.0.into_boxed_str()))
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn should_deref_to_string() {
+        let estr = EString::from("hello");
+        assert_eq!(*estr, String::from("hello"));
+    }
+
+    #[test]
+    fn should_parse_into_itself() {
+        let estr = EString::from("hello");
+        match estr.parse::<EString>() {
+            Ok(res) => assert_eq!(res, EString::from("hello")),
+            _ => unreachable!(),
+        }
+    }
+
+    #[test]
+    fn should_parse_into_string() {
+        let estr = EString::from("hello");
+        match estr.parse::<String>() {
+            Ok(res) => assert_eq!(res, String::from("hello")),
+            _ => unreachable!(),
+        }
+    }
+}
diff --git a/estring/src/core/prim.rs b/estring/src/core/prim.rs
new file mode 100644
index 0000000..ff19878
--- /dev/null
+++ b/estring/src/core/prim.rs
@@ -0,0 +1,14 @@
+//! Contains the implementations to primitive types (number, boolean)
+//!
+//! **NOTE**: Require the enabling of the same-name features
+//!
+
+#[cfg(feature = "bool")]
+mod bool;
+#[cfg(feature = "bool")]
+pub use self::bool::*;
+
+#[cfg(feature = "number")]
+mod number;
+#[cfg(feature = "number")]
+pub use self::number::*;
diff --git a/estring/src/core/prim/bool.rs b/estring/src/core/prim/bool.rs
new file mode 100644
index 0000000..f0aacc9
--- /dev/null
+++ b/estring/src/core/prim/bool.rs
@@ -0,0 +1,57 @@
+use crate::core::EString;
+use std::convert::TryFrom;
+
+impl TryFrom<EString> for bool {
+    type Error = ();
+
+    #[inline]
+    fn try_from(s: EString) -> Result<Self, Self::Error> {
+        match s.to_lowercase().as_str() {
+            "true" | "t" | "yes" | "y" | "on" | "1" => Ok(true),
+            "false" | "f" | "no" | "n" | "off" | "0" | "" => Ok(false),
+            _ => Err(()),
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::ParseError;
+
+    #[test]
+    fn should_parse_bool_variable() {
+        let test_cases = [
+            ("1", true),
+            ("0", false),
+            ("y", true),
+            ("f", false),
+            ("yes", true),
+            ("true", true),
+            ("false", false),
+            ("t", true),
+            ("f", false),
+            ("on", true),
+            ("off", false),
+        ];
+
+        for (val, expected) in test_cases {
+            let estr = EString::from(val);
+            match estr.parse::<bool>() {
+                Ok(res) => assert_eq!(res, expected),
+                _ => unreachable!(),
+            };
+        }
+    }
+
+    #[test]
+    fn should_throw_parse_error() {
+        let estr = EString::from("something");
+        match estr.parse::<bool>() {
+            Err(ParseError(orig)) => {
+                assert_eq!(orig, String::from("something"));
+            }
+            _ => unreachable!(),
+        };
+    }
+}
diff --git a/estring/src/core/prim/number.rs b/estring/src/core/prim/number.rs
new file mode 100644
index 0000000..3b93389
--- /dev/null
+++ b/estring/src/core/prim/number.rs
@@ -0,0 +1,62 @@
+use crate::core::EString;
+use std::convert::TryFrom;
+
+#[doc(hidden)]
+macro_rules! from_env_string_numbers_impl {
+    ($($ty:ty),+$(,)?) => {
+        $(
+            #[cfg(feature = "number")]
+            impl TryFrom<EString> for $ty {
+                type Error = <$ty as std::str::FromStr>::Err;
+
+                #[inline]
+                fn try_from(s: EString) -> Result<Self, Self::Error> {
+                    s.0.parse::<Self>()
+                }
+            }
+        )+
+    };
+}
+
+#[rustfmt::skip]
+from_env_string_numbers_impl![
+    i8, i16, i32, i64, i128, isize,
+    u8, u16, u32, u64, u128, usize,
+    f32, f64
+];
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::ParseError;
+
+    #[test]
+    fn should_parse_number() {
+        let estr = EString::from("-10");
+        match estr.parse::<i32>() {
+            Ok(res) => assert_eq!(res, -10),
+            _ => unreachable!(),
+        };
+    }
+
+    #[test]
+    fn should_parse_float_number() {
+        let estr = EString::from("-0.15");
+        match estr.parse::<f32>() {
+            #[allow(clippy::float_cmp)]
+            Ok(res) => assert_eq!(res, -0.15),
+            _ => unreachable!(),
+        };
+    }
+
+    #[test]
+    fn should_throw_parse_error() {
+        let estr = EString::from("-10");
+        match estr.parse::<u32>() {
+            Err(ParseError(orig)) => {
+                assert_eq!(orig, String::from("-10"));
+            }
+            _ => unreachable!(),
+        };
+    }
+}
diff --git a/estring/src/core/vec.rs b/estring/src/core/vec.rs
new file mode 100644
index 0000000..c59d45c
--- /dev/null
+++ b/estring/src/core/vec.rs
@@ -0,0 +1,153 @@
+//! Contains the implementations to vec type
+//!
+//! **NOTE**: Require the enabling of the `vec` features
+//!
+
+use crate::core::EString;
+use std::convert::TryFrom;
+use std::fmt::Write;
+
+/// Wrapper for ``Vec`` to split string by a separator (`SEP`).
+///
+/// **NOTE**: Required the enabling of the `vec` feature.
+///
+/// # Examples
+///
+/// ```rust
+/// use estring::{SepVec, EString};
+///
+/// type CommaVec<T> = SepVec<T, ','>;
+///
+/// fn main() -> Result<(), estring::ParseError> {
+///     let res = EString::from("1,2,3").parse::<CommaVec<u8>>()?;
+///     assert_eq!(*res, vec![1, 2, 3]);
+///
+///     Ok(())
+/// }
+///
+/// ```
+///
+#[derive(Debug, PartialEq, Clone)]
+pub struct SepVec<T, const SEP: char>(pub Vec<T>);
+
+impl<T, const SEP: char> std::ops::Deref for SepVec<T, SEP> {
+    type Target = Vec<T>;
+
+    #[inline]
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
+
+impl<T, const SEP: char> From<Vec<T>> for SepVec<T, SEP> {
+    #[inline]
+    fn from(vec: Vec<T>) -> Self {
+        Self(vec)
+    }
+}
+
+impl<T, const SEP: char> std::fmt::Display for SepVec<T, SEP>
+where
+    T: std::fmt::Display,
+{
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        self.0.iter().enumerate().try_for_each(|(i, part)| {
+            if i != 0 {
+                f.write_char(SEP)?;
+            }
+
+            f.write_str(&part.to_string())
+        })
+    }
+}
+
+impl<T, const SEP: char> TryFrom<EString> for SepVec<T, SEP>
+where
+    T: TryFrom<EString> + std::fmt::Display,
+{
+    type Error = T::Error;
+
+    fn try_from(value: EString) -> Result<Self, Self::Error> {
+        let inner = value
+            .split(SEP)
+            .map(str::trim)
+            .map(EString::from)
+            .map(T::try_from)
+            .collect::<Result<Vec<_>, _>>()?;
+        Ok(Self(inner))
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    const COMMA: char = ',';
+    const SEMI: char = ';';
+
+    type CommaVec<T> = SepVec<T, COMMA>;
+    type SemiVec<T> = SepVec<T, SEMI>;
+
+    #[test]
+    fn should_parse_into_vec() {
+        let estr = EString::from("a,b,c,d,e");
+        match estr.parse::<CommaVec<&str>>() {
+            Ok(res) => assert_eq!(*res, vec!["a", "b", "c", "d", "e"]),
+            _ => unreachable!(),
+        };
+    }
+
+    #[test]
+    fn should_trim_identations_before_parsing() {
+        let input = "
+a , b, c,
+d,e";
+        let estr = EString::from(input);
+        match estr.parse::<CommaVec<&str>>() {
+            Ok(res) => assert_eq!(*res, vec!["a", "b", "c", "d", "e"]),
+            _ => unreachable!(),
+        };
+    }
+
+    #[test]
+    fn should_parse_into_vector_of_vectors() {
+        let estr = EString::from("a,b; c,d,e; f,g");
+        match estr.parse::<SemiVec<CommaVec<&str>>>() {
+            Ok(res) => assert_eq!(
+                res,
+                SemiVec::from(vec![
+                    CommaVec::from(vec!["a", "b"]),
+                    CommaVec::from(vec!["c", "d", "e"]),
+                    CommaVec::from(vec!["f", "g"])
+                ])
+            ),
+            _ => unreachable!(),
+        };
+    }
+
+    #[cfg(feature = "number")]
+    mod numbers {
+        use super::*;
+        use crate::ParseError;
+
+        #[test]
+        fn should_parse_into_num_vec() {
+            let estr = EString::from("1,2,3,4,5");
+            match estr.parse::<CommaVec<i32>>() {
+                Ok(res) => assert_eq!(*res, vec![1, 2, 3, 4, 5]),
+                _ => unreachable!(),
+            };
+        }
+
+        #[test]
+        fn should_throw_parse_vec_error() {
+            let estr = EString::from("1,2,3,4,5");
+            match estr.parse::<SemiVec<i32>>() {
+                Err(ParseError(orig)) => {
+                    assert_eq!(orig, String::from("1,2,3,4,5"));
+                }
+                _ => unreachable!(),
+            };
+        }
+    }
+}
diff --git a/estring/src/error.rs b/estring/src/error.rs
new file mode 100644
index 0000000..a484b68
--- /dev/null
+++ b/estring/src/error.rs
@@ -0,0 +1,19 @@
+/// Failed to parse the specified string.
+#[derive(Debug)]
+pub struct ParseError(pub String);
+
+impl std::fmt::Display for ParseError {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        write!(f, r#"Failed to parse: "{}""#, self.0)
+    }
+}
+
+impl std::error::Error for ParseError {}
+
+impl std::ops::Deref for ParseError {
+    type Target = String;
+
+    fn deref(&self) -> &Self::Target {
+        &self.0
+    }
+}
diff --git a/estring/src/lib.rs b/estring/src/lib.rs
new file mode 100644
index 0000000..e38b638
--- /dev/null
+++ b/estring/src/lib.rs
@@ -0,0 +1,72 @@
+//!
+//! # ``EString``
+//!
+//! A simple way to parse a string using type annotations.
+//!
+//! This package was originally designed for [enve]
+//!
+//! [enve]: https://github.com/pleshevskiy/itconfig-rs
+//!
+//! ## Getting started
+//!
+//! ```rust
+//! use estring::{SepVec, EString};
+//!
+//! type PlusVec<T> = SepVec<T, '+'>;
+//! type MulVec<T> = SepVec<T, '*'>;
+//!
+//! fn main() -> Result<(), estring::ParseError> {
+//!     let res = EString::from("10+5*2+3")
+//!         .parse::<PlusVec<MulVec<f32>>>()?
+//!         .iter()
+//!         .map(|m| m.iter().product::<f32>())
+//!         .sum::<f32>();
+//!
+//!     assert_eq!(res, 23.0);
+//!     Ok(())
+//! }
+//! ```
+//!
+//! ## Installation
+//!
+//! **The MSRV is 1.51.0**
+//!
+//! Add `estring = { version = "0.1", features = ["vec", "number"] }` as a
+//! dependency in `Cargo.toml`.
+//!
+//! `Cargo.toml` example:
+//!
+//! ```toml
+//! [package]
+//! name = "my-crate"
+//! version = "0.1.0"
+//! authors = ["Me <user@rust-lang.org>"]
+//!
+//! [dependencies]
+//! estring = { version = "0.1", features = ["vec", "number"] }
+//! ```
+//!
+//! ## License
+//!
+//! **MIT**.
+//!
+//! See [LICENSE](./LICENSE) to see the full text.
+//!
+#![deny(clippy::pedantic)]
+#![allow(clippy::module_name_repetitions)]
+#![deny(missing_docs)]
+
+pub mod core;
+mod error;
+
+pub use crate::core::*;
+pub use crate::error::ParseError;
+
+#[cfg(test)]
+mod tests {
+    #[test]
+    fn it_works() {
+        let result = 2 + 2;
+        assert_eq!(result, 4);
+    }
+}
diff --git a/examples/calc.rs b/examples/calc.rs
index 3460667..129b488 100644
--- a/examples/calc.rs
+++ b/examples/calc.rs
@@ -1,4 +1,4 @@
-use enve::core::SepVec;
+use enve::estr::SepVec;
 
 type MinusVec<T> = SepVec<T, '-'>;
 type PlusVec<T> = SepVec<T, '+'>;
diff --git a/src/core.rs b/src/core.rs
index 95a9f85..61712a4 100644
--- a/src/core.rs
+++ b/src/core.rs
@@ -1,65 +1,238 @@
-#[cfg(any(feature = "number", feature = "bool"))]
-pub mod prim;
-#[cfg(any(feature = "number", feature = "bool"))]
-pub use prim::*;
-
-#[cfg(feature = "vec")]
-pub mod vec;
-#[cfg(feature = "vec")]
-pub use vec::*;
-
 use crate::error::Error;
-use std::convert::{Infallible, TryFrom};
+use estring::EString;
+use std::convert::TryFrom;
 
-/// Wrapper under String type.
-///
-/// When we read the environment variable, we automatically convert the value
-/// to EnvString and then convert it to your expected type.
-///
-#[derive(Debug, Default, PartialEq, Eq, Clone)]
-pub struct EString(String);
-
-impl EString {
-    #[inline]
-    pub fn parse<T: TryFrom<EString>>(self) -> Result<T, Error> {
-        let orig = self.0.clone();
-        <T as TryFrom<EString>>::try_from(self).map_err(|_| Error::Parse(orig))
-    }
-}
-
-impl<T> From<T> for EString
+pub fn get_or_set_default<R>(env_name: &str, default: R) -> Result<R, Error>
 where
-    T: std::fmt::Display,
+    R: TryFrom<EString> + std::fmt::Display,
 {
-    #[inline]
-    fn from(val: T) -> Self {
-        Self(val.to_string())
-    }
+    get::<R>(env_name).or_else(|err| match err {
+        Error::NotPresent => sset(env_name, &default).parse().map_err(Error::from),
+        _ => Err(err),
+    })
 }
 
-impl std::ops::Deref for EString {
-    type Target = String;
-
-    #[inline]
-    fn deref(&self) -> &Self::Target {
-        &self.0
-    }
+pub fn get<R>(env_name: &str) -> Result<R, Error>
+where
+    R: TryFrom<EString>,
+{
+    sget(env_name).and_then(|v| v.parse().map_err(Error::from))
 }
 
-impl TryFrom<EString> for String {
-    type Error = Infallible;
-
-    #[inline]
-    fn try_from(s: EString) -> Result<Self, Self::Error> {
-        Ok(s.0)
-    }
+pub fn sget(env_name: &str) -> Result<EString, Error> {
+    std::env::var(env_name)
+        .map_err(Error::from)
+        .map(EString::from)
 }
 
-impl TryFrom<EString> for &'static str {
-    type Error = Infallible;
+pub fn sset<V>(env_name: &str, value: V) -> EString
+where
+    V: std::fmt::Display,
+{
+    let val = value.to_string();
+    std::env::set_var(env_name, &val);
+    val.into()
+}
 
-    #[inline]
-    fn try_from(s: EString) -> Result<Self, Self::Error> {
-        Ok(Box::leak(s.0.into_boxed_str()))
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    struct TestCase<const N: u8>;
+
+    impl<const N: u8> std::fmt::Display for TestCase<N> {
+        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+            write!(f, "test_case_{}", N)
+        }
+    }
+
+    #[test]
+    fn should_add_env_variable_to_process() {
+        let en = TestCase::<0>.to_string();
+        sset(&en, "hello");
+        match std::env::var(&en) {
+            Ok(var) => assert_eq!(&var, "hello"),
+            _ => unreachable!(),
+        }
+    }
+
+    #[test]
+    fn should_return_variable() {
+        let en = TestCase::<1>.to_string();
+        std::env::set_var(&en, "hello");
+        match get::<&str>(&en) {
+            Ok(res) => assert_eq!(res, "hello"),
+            _ => unreachable!(),
+        };
+    }
+
+    #[test]
+    fn should_throw_no_present_error() {
+        let en = TestCase::<2>.to_string();
+        match get::<&str>(&en) {
+            Err(Error::NotPresent) => {}
+            _ => unreachable!(),
+        };
+    }
+
+    #[test]
+    fn should_set_default_if_var_is_no_present() {
+        let en = TestCase::<3>.to_string();
+        let orig = "hello";
+        match get_or_set_default(&en, orig) {
+            Ok(res) => {
+                assert_eq!(res, orig);
+                assert_eq!(std::env::var(&en).unwrap(), orig);
+            }
+            _ => unreachable!(),
+        };
+    }
+
+    #[cfg(feature = "number")]
+    mod numbers {
+        use super::*;
+
+        #[test]
+        fn should_return_parsed_num() {
+            let en = TestCase::<4>.to_string();
+            std::env::set_var(&en, "-10");
+            match get::<i32>(&en) {
+                Ok(res) => assert_eq!(res, -10),
+                _ => unreachable!(),
+            };
+        }
+
+        #[test]
+        fn should_throw_parse_error() {
+            let en = TestCase::<5>.to_string();
+            std::env::set_var(&en, "-10");
+            match get::<u32>(&en) {
+                Err(Error::Parse(orig)) => {
+                    assert_eq!(orig, String::from("-10"))
+                }
+                _ => unreachable!(),
+            };
+        }
+
+        #[test]
+        fn should_set_default_num_if_var_is_no_present() {
+            let en = TestCase::<6>.to_string();
+            let orig = 10;
+            match get_or_set_default(&en, orig) {
+                Ok(res) => {
+                    assert_eq!(res, orig);
+                    assert_eq!(std::env::var(&en).unwrap(), "10");
+                }
+                _ => unreachable!(),
+            };
+        }
+    }
+
+    #[cfg(feature = "bool")]
+    mod boolean {
+        use super::*;
+
+        #[test]
+        fn should_parse_bool_variable() {
+            let en = TestCase::<7>.to_string();
+
+            [
+                ("1", true),
+                ("y", true),
+                ("yes", true),
+                ("true", true),
+                ("t", true),
+                ("on", true),
+                ("false", false),
+                ("f", false),
+                ("0", false),
+            ]
+            .iter()
+            .for_each(|(val, expected)| {
+                let mut en = en.clone();
+                en.push_str(val.as_ref());
+
+                std::env::set_var(&en, val);
+                match get::<bool>(&en) {
+                    Ok(res) => assert_eq!(res, *expected),
+                    _ => unreachable!(),
+                };
+            })
+        }
+    }
+
+    #[cfg(feature = "vec")]
+    mod vector {
+        use super::*;
+        use crate::estr::{CommaVec, SemiVec, SepVec};
+
+        #[test]
+        fn should_return_var_as_vector() {
+            let en = TestCase::<8>.to_string();
+
+            std::env::set_var(&en, "1,2,3,4,5");
+            match get::<CommaVec<i32>>(&en) {
+                Ok(res) => assert_eq!(*res, vec![1, 2, 3, 4, 5]),
+                _ => unreachable!(),
+            };
+        }
+
+        #[test]
+        fn should_trim_identations_before_parsing() {
+            let en = TestCase::<9>.to_string();
+
+            let input = "
+1 , 2, 3,
+4,5";
+
+            std::env::set_var(&en, input);
+            match get::<CommaVec<i32>>(&en) {
+                Ok(res) => assert_eq!(*res, vec![1, 2, 3, 4, 5]),
+                _ => unreachable!(),
+            };
+        }
+
+        #[test]
+        fn should_return_vector_of_vectors() {
+            let en = TestCase::<10>.to_string();
+
+            std::env::set_var(&en, "1,2; 3,4,5; 6,7");
+            match get::<SemiVec<CommaVec<i32>>>(&en) {
+                Ok(res) => assert_eq!(
+                    res,
+                    SemiVec::from(vec![
+                        CommaVec::from(vec![1, 2]),
+                        CommaVec::from(vec![3, 4, 5]),
+                        CommaVec::from(vec![6, 7])
+                    ])
+                ),
+                _ => unreachable!(),
+            };
+        }
+
+        #[test]
+        fn should_throw_parse_vec_error() {
+            let en = TestCase::<11>.to_string();
+            std::env::set_var(&en, "1,2,3,4,5");
+            match get::<SepVec<i32, '+'>>(&en) {
+                Err(Error::Parse(orig)) => {
+                    assert_eq!(orig, String::from("1,2,3,4,5"))
+                }
+                _ => unreachable!(),
+            };
+        }
+
+        #[test]
+        fn should_set_default_vector_if_var_is_no_present() {
+            let en = TestCase::<12>.to_string();
+            let orig = CommaVec::from(vec![1, 2, 3, 4]);
+            match get_or_set_default(&en, orig.clone()) {
+                Ok(res) => {
+                    assert_eq!(res, orig);
+                    assert_eq!(std::env::var(&en).unwrap(), "1,2,3,4");
+                }
+                _ => unreachable!(),
+            };
+        }
     }
 }
diff --git a/src/core/prim.rs b/src/core/prim.rs
deleted file mode 100644
index d0ba318..0000000
--- a/src/core/prim.rs
+++ /dev/null
@@ -1,39 +0,0 @@
-use crate::core::EString;
-use std::convert::{Infallible, TryFrom};
-
-#[doc(hidden)]
-macro_rules! from_env_string_numbers_impl {
-    ($($ty:ty),+$(,)?) => {
-        $(
-            #[cfg(feature = "number")]
-            impl TryFrom<EString> for $ty {
-                type Error = <$ty as std::str::FromStr>::Err;
-
-                #[inline]
-                fn try_from(s: EString) -> Result<Self, Self::Error> {
-                    s.0.parse::<Self>()
-                }
-            }
-        )+
-    };
-}
-
-#[rustfmt::skip]
-from_env_string_numbers_impl![
-    i8, i16, i32, i64, i128, isize,
-    u8, u16, u32, u64, u128, usize,
-    f32, f64
-];
-
-#[cfg(feature = "bool")]
-impl TryFrom<EString> for bool {
-    type Error = Infallible;
-
-    #[inline]
-    fn try_from(s: EString) -> Result<Self, Self::Error> {
-        Ok(matches!(
-            s.to_lowercase().as_str(),
-            "true" | "t" | "yes" | "y" | "on" | "1"
-        ))
-    }
-}
diff --git a/src/core/vec.rs b/src/core/vec.rs
deleted file mode 100644
index cc2a76a..0000000
--- a/src/core/vec.rs
+++ /dev/null
@@ -1,60 +0,0 @@
-use crate::core::EString;
-use std::convert::TryFrom;
-use std::fmt::Write;
-
-pub const COMMA: char = ',';
-pub const SEMI: char = ';';
-
-pub type CommaVec<T> = SepVec<T, COMMA>;
-pub type SemiVec<T> = SepVec<T, SEMI>;
-
-#[derive(Debug, PartialEq, Clone)]
-pub struct SepVec<T, const SEP: char>(pub Vec<T>);
-
-impl<T, const SEP: char> std::ops::Deref for SepVec<T, SEP> {
-    type Target = Vec<T>;
-
-    #[inline]
-    fn deref(&self) -> &Self::Target {
-        &self.0
-    }
-}
-
-impl<T, const SEP: char> From<Vec<T>> for SepVec<T, SEP> {
-    #[inline]
-    fn from(vec: Vec<T>) -> Self {
-        Self(vec)
-    }
-}
-
-impl<T, const SEP: char> std::fmt::Display for SepVec<T, SEP>
-where
-    T: std::fmt::Display,
-{
-    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-        self.0.iter().enumerate().try_for_each(|(i, part)| {
-            if i != 0 {
-                f.write_char(SEP)?;
-            }
-
-            f.write_str(&part.to_string())
-        })
-    }
-}
-
-impl<T, const SEP: char> TryFrom<EString> for SepVec<T, SEP>
-where
-    T: TryFrom<EString> + std::fmt::Display,
-{
-    type Error = T::Error;
-
-    fn try_from(value: EString) -> Result<Self, Self::Error> {
-        let inner = value
-            .split(SEP)
-            .map(|p| p.trim())
-            .map(EString::from)
-            .map(T::try_from)
-            .collect::<Result<Vec<_>, _>>()?;
-        Ok(Self(inner))
-    }
-}
diff --git a/src/error.rs b/src/error.rs
index 002554e..a6ce455 100644
--- a/src/error.rs
+++ b/src/error.rs
@@ -4,7 +4,7 @@ use std::ffi::OsString;
 use std::fmt;
 
 /// The error type for operations interacting with environment variables
-#[derive(Debug, PartialEq)]
+#[derive(Debug)]
 pub enum Error {
     /// The specified environment variable was not present in the current process's environment.
     NotPresent,
@@ -45,3 +45,9 @@ impl From<VarError> for Error {
         }
     }
 }
+
+impl From<estring::ParseError> for Error {
+    fn from(err: estring::ParseError) -> Self {
+        Error::Parse(err.clone())
+    }
+}
diff --git a/src/estr.rs b/src/estr.rs
new file mode 100644
index 0000000..e0fe52c
--- /dev/null
+++ b/src/estr.rs
@@ -0,0 +1,6 @@
+#[cfg(feature = "vec")]
+pub mod vec;
+#[cfg(feature = "vec")]
+pub use vec::{CommaVec, SemiVec};
+
+pub use estring::core::*;
diff --git a/src/estr/vec.rs b/src/estr/vec.rs
new file mode 100644
index 0000000..4307856
--- /dev/null
+++ b/src/estr/vec.rs
@@ -0,0 +1,7 @@
+use estring::SepVec;
+
+const COMMA: char = ',';
+const SEMI: char = ';';
+
+pub type CommaVec<T> = SepVec<T, COMMA>;
+pub type SemiVec<T> = SepVec<T, SEMI>;
diff --git a/src/lib.rs b/src/lib.rs
index d442af4..ebf8312 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -137,24 +137,25 @@
 #![forbid(non_ascii_idents)]
 #![deny(
     missing_debug_implementations,
-    // missing_docs,
+    missing_docs,
     unstable_features,
     unused_imports,
     unused_qualifications
 )]
+#![warn(missing_docs)]
 // Clippy lints
 #![deny(clippy::all)]
 #![allow(clippy::needless_doctest_main)]
 
 /////////////////////////////////////////////////////////////////////////////
 
-pub mod core;
+mod core;
 mod error;
-mod utils;
+pub mod estr;
 
 pub use self::core::*;
-pub use self::error::*;
-pub use self::utils::*;
+pub use self::core::{get, get_or_set_default, sget, sset};
+pub use self::error::Error;
 
 #[cfg(feature = "macro")]
 extern crate enve_mod;
diff --git a/src/utils.rs b/src/utils.rs
deleted file mode 100644
index 5673892..0000000
--- a/src/utils.rs
+++ /dev/null
@@ -1,236 +0,0 @@
-use crate::core::EString;
-use crate::error::Error;
-use std::convert::TryFrom;
-use std::env;
-
-pub fn get_or_set_default<R>(env_name: &str, default: R) -> Result<R, Error>
-where
-    R: TryFrom<EString> + std::fmt::Display,
-{
-    get::<R>(env_name).or_else(|err| match err {
-        Error::NotPresent => set(env_name, &default).parse(),
-        _ => Err(err),
-    })
-}
-
-pub fn get<R>(env_name: &str) -> Result<R, Error>
-where
-    R: TryFrom<EString>,
-{
-    env::var(env_name)
-        .map_err(From::from)
-        .map(EString::from)
-        .and_then(EString::parse)
-}
-
-pub fn set<V>(env_name: &str, value: V) -> EString
-where
-    V: std::fmt::Display,
-{
-    let val = value.to_string();
-    env::set_var(env_name, &val);
-    val.into()
-}
-
-#[cfg(test)]
-mod tests {
-    use super::*;
-
-    struct TestCase<const N: u8>;
-
-    impl<const N: u8> std::fmt::Display for TestCase<N> {
-        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
-            write!(f, "test_case_{}", N)
-        }
-    }
-
-    #[test]
-    fn should_add_env_variable_to_process() {
-        let en = TestCase::<0>.to_string();
-        set(&en, "hello");
-        match env::var(&en) {
-            Ok(var) => assert_eq!(&var, "hello"),
-            _ => unreachable!(),
-        }
-    }
-
-    #[test]
-    fn should_return_variable() {
-        let en = TestCase::<1>.to_string();
-        env::set_var(&en, "hello");
-        match get::<&str>(&en) {
-            Ok(res) => assert_eq!(res, "hello"),
-            _ => unreachable!(),
-        };
-    }
-
-    #[test]
-    fn should_throw_no_present_error() {
-        let en = TestCase::<2>.to_string();
-        match get::<&str>(&en) {
-            Err(Error::NotPresent) => {}
-            _ => unreachable!(),
-        };
-    }
-
-    #[test]
-    fn should_set_default_if_var_is_no_present() {
-        let en = TestCase::<3>.to_string();
-        let orig = "hello";
-        match get_or_set_default(&en, orig) {
-            Ok(res) => {
-                assert_eq!(res, orig);
-                assert_eq!(env::var(&en).unwrap(), orig);
-            }
-            _ => unreachable!(),
-        };
-    }
-
-    #[cfg(feature = "number")]
-    mod numbers {
-        use super::*;
-
-        #[test]
-        fn should_return_parsed_num() {
-            let en = TestCase::<4>.to_string();
-            env::set_var(&en, "-10");
-            match get::<i32>(&en) {
-                Ok(res) => assert_eq!(res, -10),
-                _ => unreachable!(),
-            };
-        }
-
-        #[test]
-        fn should_throw_parse_error() {
-            let en = TestCase::<5>.to_string();
-            env::set_var(&en, "-10");
-            match get::<u32>(&en) {
-                Err(Error::Parse(orig)) => {
-                    assert_eq!(orig, String::from("-10"))
-                }
-                _ => unreachable!(),
-            };
-        }
-
-        #[test]
-        fn should_set_default_num_if_var_is_no_present() {
-            let en = TestCase::<6>.to_string();
-            let orig = 10;
-            match get_or_set_default(&en, orig) {
-                Ok(res) => {
-                    assert_eq!(res, orig);
-                    assert_eq!(env::var(&en).unwrap(), "10");
-                }
-                _ => unreachable!(),
-            };
-        }
-    }
-
-    #[cfg(feature = "bool")]
-    mod boolean {
-        use super::*;
-
-        #[test]
-        fn should_parse_bool_variable() {
-            let en = TestCase::<7>.to_string();
-
-            [
-                ("1", true),
-                ("y", true),
-                ("yes", true),
-                ("true", true),
-                ("t", true),
-                ("on", true),
-                ("false", false),
-                ("f", false),
-                ("0", false),
-            ]
-            .iter()
-            .for_each(|(val, expected)| {
-                let mut en = en.clone();
-                en.push_str(val.as_ref());
-
-                env::set_var(&en, val);
-                match get::<bool>(&en) {
-                    Ok(res) => assert_eq!(res, *expected),
-                    _ => unreachable!(),
-                };
-            })
-        }
-    }
-
-    #[cfg(feature = "vec")]
-    mod vector {
-        use super::*;
-        use crate::core::vec::{CommaVec, SemiVec, SepVec};
-
-        #[test]
-        fn should_return_var_as_vector() {
-            let en = TestCase::<8>.to_string();
-
-            env::set_var(&en, "1,2,3,4,5");
-            match get::<CommaVec<i32>>(&en) {
-                Ok(res) => assert_eq!(*res, vec![1, 2, 3, 4, 5]),
-                _ => unreachable!(),
-            };
-        }
-
-        #[test]
-        fn should_trim_identations_before_parsing() {
-            let en = TestCase::<9>.to_string();
-
-            let input = "
-1 , 2, 3,
-4,5";
-
-            env::set_var(&en, input);
-            match get::<CommaVec<i32>>(&en) {
-                Ok(res) => assert_eq!(*res, vec![1, 2, 3, 4, 5]),
-                _ => unreachable!(),
-            };
-        }
-
-        #[test]
-        fn should_return_vector_of_vectors() {
-            let en = TestCase::<10>.to_string();
-
-            env::set_var(&en, "1,2; 3,4,5; 6,7");
-            match get::<SemiVec<CommaVec<i32>>>(&en) {
-                Ok(res) => assert_eq!(
-                    res,
-                    SemiVec::from(vec![
-                        CommaVec::from(vec![1, 2]),
-                        CommaVec::from(vec![3, 4, 5]),
-                        CommaVec::from(vec![6, 7])
-                    ])
-                ),
-                _ => unreachable!(),
-            };
-        }
-
-        #[test]
-        fn should_throw_parse_vec_error() {
-            let en = TestCase::<11>.to_string();
-            env::set_var(&en, "1,2,3,4,5");
-            match get::<SepVec<i32, '+'>>(&en) {
-                Err(Error::Parse(orig)) => {
-                    assert_eq!(orig, String::from("1,2,3,4,5"))
-                }
-                _ => unreachable!(),
-            };
-        }
-
-        #[test]
-        fn should_set_default_vector_if_var_is_no_present() {
-            let en = TestCase::<12>.to_string();
-            let orig = CommaVec::from(vec![1, 2, 3, 4]);
-            match get_or_set_default(&en, orig.clone()) {
-                Ok(res) => {
-                    assert_eq!(res, orig);
-                    assert_eq!(env::var(&en).unwrap(), "1,2,3,4");
-                }
-                _ => unreachable!(),
-            };
-        }
-    }
-}