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Iterators and Closures.md

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+# Functional Language Features: Iterators and Closures
+Rust's design has taken inspiration from many exisitng languages and techniques
+
+One significant influence is *functional programming*
+
+Programming in a functional style often include using functions as values by passing them in args, returning them form other unfcitons, assigning them to varaibles for later execution and so forth.
+
+This chapter/section won't debate the issue of what functional programming is or isn't.
+
+It will discuss some features of Rust that are similar to features in many languages often referred to as functional
+
+It will cover:
+- [*Closures*](./Closures.md) - a function-like construct you can store in a variable
+- [*Iterators*](./Iterators.md) - a way of processing a series of elements
+- How to use colsure and iterators to improve the I/O project (minigrep)
+- The preformance of closures and iterators (Spoiler alert: they are faster than you might think!)
+
+We have already covered some other Rust freatures, such as pattern matchin and enums, that are also influenced by the functional style.
+
+Mastering closures and iterators is an improtant part of wiritng idiomatic, fast Rust code.