Avoid default parameters

Author: WillQu

README.md

@@ -24,6 +24,7 @@ Rules in **bold** are the most important ones.
     - [PREFER] Use value classes when possible
     - [PREFER] Do not use `lazy`
     - [MUST] Do not pattern match on `Throwable`, use `NonFatal(e)`
+    - [[PREFER] Do not use default parameters](guidelines/scala/avoid-default-parameters.md)
 1. Functional programming
     - **[PREFER] Use pure functions as much as possible**
     - [PREFER] By default, use immutable values
@@ -58,3 +59,4 @@ They are here just as a source of inspiration, they are not included in our guid
 - [Databricks best practices](https://github.com/databricks/scala-style-guide)
 - [PayPal best practices](https://github.com/paypal/scala-style-guide)
 - [Twitter best practices](http://twitter.github.io/effectivescala)
+- [Why are Default Parameter Values Considered Bad in Scala?](https://blog.ssanj.net/posts/2019-05-01-why-are-default-parameter-values-considered-bad-in-scala.html)

guidelines/scala/avoid-default-parameters.md

@@ -0,0 +1,7 @@
+# Avoid default parameters
+Default parameters are convenient but have a number of issues:
+- Unclear code
+- Hard to use currying and partial application
+- Subtle bugs that would be otherwise catched by the compiler
+
+See [https://blog.ssanj.net/posts/2019-05-01-why-are-default-parameter-values-considered-bad-in-scala.html]

guidelines/scala/do-not-abuse-of-primitive-types.md

@@ -1,6 +1,6 @@
 # Do not abuse of primitive types
 
-This is a well known code small named [Primitive Obsession](https://www.franzoni.eu/primitive-types-are-not-your-friends/), often due to developer laziness.
+This is a well known code smell named [Primitive Obsession](https://www.franzoni.eu/primitive-types-are-not-your-friends/), often due to developer laziness.
 
 When you manipulate a lot of `String`, `Int` or `Boolean`, it becomes harder and harder to know what they contain and do not make mistakes manipulating them.