Today I Learned

A Hashrocket project

Destructuring Record in Fn Argument

Elm has destructuring/pattern matching that feels typical for an ML. One pattern matching feature I like is record destructuring in a function argument.

myRecord = {a = 1}

myFunc {a} = a

myFunc myRecord
# 1

Here, we destructure the key a out of the record. What’s cool about this is the record does not need to match exactly, but can be any record with the property of a.

myRecord = {a = 1, b = 2}

myFunc {a} = a

myFunc myRecord
# 1

This enables us to be able to grow the record over time without changing the signature of the function. In Elm, not having to accomodate that change across the entire program is great.