dillon1000/react

Example of "unnecessary" memoization of lambdas

I noticed this while demoing Forget to React Org alum Christoph Nakazawa — in 
array.map calls (and other APIs that take a lambda as input) we sometimes end up 
memoizing the lambda. It's technically correct since the function _could_ return 
the lambda, and then we'd need it to be memoized. It's tricky because array.map 
is often called on nested objects, where even if we had type inference on the 
outer value we wouldn't know for sure that the inner property is an Array and 
not some other data type with a custom .map. For example in 
`data.feedback.comments.edges.map(edge => ...)`, even if we knew that `data` was 
an Object, we wouldn't know that data.feedback.comments.edges is an Array 
without cross-file type knowledge. 

But it's definitely wasteful to memoize these lambdas, so we should brainstorm 
options. One option that stands out right away: if the lambda has zero 
dependencies, then we could lift it out to module scope and refer to it by name.