Local Bindings

You can bind local variables inside functions using (let [name value] body). Bindings can be chained and each name is in scope for the body of the local binding.

As an example below we have a function called circle_area which:

• takes one argument r
• binds data to two local variables pi and r_sq using a local let binding
• returns the area of the circle

(let circle_area {r}
  (let [pi   3.14159
        r_sq (*. r r)]
    (*. pi r_sq)))

Note:

• like function names local let bindings, by convention, use snake_case identifiers
• this function has the type Float -> Float which Mond infers because of the use of *.