Ref: Clojure from the ground up: Functions
Functions are verbs.
We can define symbols to values that will not change (called immutable) using let.
These symbols are only available with an expression (“scoped”). The symbols can be overriden to point to a different value.
def allows us to define mutable variables. These are helpful for experimentation.
defn is a shorthand to define functions.
The chapter builds an extremely powerful intuition behind the relation between let and functions.
Also, it’s helpful to think about functions as “common patterns of computation”. While problem solving, I’m starting to adopt this approach as well:
- Look for patterns in the problem.
- Formulate a function to solve a simple pattern.
- Combine multiple patterns to solve the bigger problems. (composition using standard library functions)
This is core pursuit of software engineering: organizing expressions. Almost every programming language is in search of the right tools to break apart, name, and recombine expressions to solve large problems.
I find this really insightful. Often, our mental models are constrained by the programming langauge we use. The way a backend engineer approaches a problem is quite different from a frontend engineer. I experienced this in a sense when I switched from Python to Go as my preferred language. And now, learning LISP (Racket, Clojure) has afforded me an even simpler way to approach problems.