jessitron The first useful bit of functional programming is the map method on List. It gives us a new List, which contains the results of the mapped function applied to each item in the list. We might think of it like this, mapping f over a List of a single item of type A: That’s the … Read moreFrom lists to trains to functors
TL;DR – it’s a good idea to throw experimental changes on a branch instead of stashing them. Today I stashed some changes, then popped them out, then decided they were a failure and wiped them out, then (later) wanted them back. git stash makes a commit, and commits are not deleted for thirty days, so … Read moregit: I want my stash back
A good novelist makes every piece of the story essential to the final resolution. Each event described in the book leads up to one big finale. That’s a good narrative. We like to see the past in that light. We like to believe everything happens for a reason, and that reason is to get things … Read morePlan backwards, look forward
Looking at other cultures, finding differences, can teach us about ourselves. One example from business: in the US we rate managers on results. Quarterly or annual metrics measure an employee’s value. In contrast, many Asian countries give managers years to build a strong market position. Recognizing the distinction between short-term and long-term results, we can … Read moreLooking across the lines
With git, source code lives in a single working directory. When we switch from one branch to another, git rearranges our files for us. Usually this keeps things simple, but now and then I wish for two copies of the code. Do you ever want to run a big fat suite of tests in one … Read moreGit: Checkout multiple branches at the same time
TL;DR – Scala lets you expose internal data, then later change underpinnings while maintaining the same interface. The functional Way is an open Way. Internal data is available to anyone who wishes to extract it. “But what about encapsulation??” – horrified OO programmer“We do not fear your code, for you cannot screw up our immutable … Read moreData Exposure and Encapsulation
Quote: At first I wrote flexible code. I figured that because I couldn’t predict the future, I better leave all the options open. The code was modularized, well-factored, with a lot of bells and whistles, and more than enough documentation. I was proud of it, until I learned that: Things changed so rapidly that even … Read moreEvolution of a developer
Back in the Smalltalk days when OO was birthed, the idea was to have a bunch of objects that pass messages to each other. The focus was supposed to be on the messages. But people like objects. They are easy to draw on a white board. And they come with cool tools like inheritance and … Read moreTools vs Self-restraint, and a Dystopian vision of FP
Applicative functor: you wrap some food in a tortilla, you wrap the microwave in a tortilla, and you get hot food in a tortilla!— Jessica Kerr (@jessitron) September 10, 2013 But why would you do that?? Say you have a collection of document IDs and you are going to retrievethe documents from the database. Not … Read moreA realistic use case for applicative functors
If some team members use git-svn locally, they might have a local working branch. When the team moves to a central git repository, that work needs to come with them. In the old git-svn repo: 1) Find the revision where the local branch of interest branched off master: git svn find-rev `git merge-base $branch master` … Read moreConverting from svn to git: salvaging local branches