refactor(router): move fp_utils module to common_utils crate (#391)

Co-authored-by: Arun Raj M <jarnura47@gmail.com>
Co-authored-by: Nishant Joshi <nishant.joshi@juspay.in>

crates/common_utils/src/fp_utils.rs

@@ -1,6 +1,13 @@
+//! Functional programming utilities
+
+/// The Applicative trait provides a pure behavior,
+/// which can be used to create values of type f a from values of type a.
 pub trait Applicative<R> {
+    /// The Associative type acts as a (f a) wrapper for Self.
     type WrappedSelf<T>;
 
+    /// Applicative::pure(_) is abstraction with lifts any arbitrary type to underlying higher
+    /// order type
     fn pure(v: R) -> Self::WrappedSelf<R>;
 }
 
@@ -18,7 +25,8 @@ impl<R, E> Applicative<R> for Result<R, E> {
     }
 }
 
-// This function allows lazy evaluation of the `f` argument
+/// This function wraps the evaluated result of `f` into current context,
+/// based on the condition provided into the `predicate`
 pub fn when<W: Applicative<(), WrappedSelf<()> = W>, F>(predicate: bool, f: F) -> W
 where
     F: FnOnce() -> W,

crates/common_utils/src/lib.rs

@@ -7,6 +7,7 @@ pub mod crypto;
 pub mod custom_serde;
 pub mod errors;
 pub mod ext_traits;
+pub mod fp_utils;
 pub mod pii;
 pub mod validation;
 

crates/router/src/utils.rs

@@ -1,7 +1,6 @@
 pub(crate) mod custom_serde;
 pub(crate) mod db_utils;
 mod ext_traits;
-mod fp_utils;
 
 #[cfg(feature = "kv_store")]
 pub(crate) mod storage_partitioning;
@@ -9,14 +8,12 @@ pub(crate) mod storage_partitioning;
 pub(crate) use common_utils::{
     crypto,
     ext_traits::{ByteSliceExt, BytesExt, Encode, StringExt, ValueExt},
+    fp_utils::when,
     validation::validate_email,
 };
 use nanoid::nanoid;
 
-pub(crate) use self::{
+pub(crate) use self::ext_traits::{OptionExt, ValidateCall};
-    ext_traits::{OptionExt, ValidateCall},
-    fp_utils::when,
-};
 use crate::consts;
 
 pub mod error_parser {