martin odersky

This is a page from my book, Functional Programming, Simplified

What is This “Lambda” You Speak Of?

“It takes a wise man to learn from his mistakes, but an even wiser man to learn from others.”

~ Zen Proverb

Goals

Once you get into FP, you’ll quickly start hearing the terms “lambda” and “lambda calculus.” The goal of this chapter is to provide background information on where those names come from, and what they mean.

Researching the use of an IO Monad in Scala

As I was researching who might be using an “IO Monad” in Scala, I found this quote from Martin Odersky in the Google Group titled “scala-debate”:

“The IO monad was a neat trick for combining side effects with lazy evaluation ... there is only one lazily evaluated language in wide usage today and even its creators have said that laziness was probably a mistake. Strict languages don’t need the IO monad, and generally don’t have it, even though they could. Bob Harper’s posts in his ‘existential type’ series are a good explanation on why not.”

Here’s a link to Bob Harper’s The Point of Laziness article.

What does '???' (three question marks) mean in Scala?

Scala FAQ: What does the use of three questions marks (???) in Scala mean?

The syntax of using three question marks in Scala lets you write a not-yet implemented method, like this:

def createWorldPeace = ???

The methods you define can also take input parameters and specify a return type, like this:

Software code too fluid to test right now

I love this comment from Martin Odersky, from the image shown, which comes from this link:

“Initially, things were too fluid to invest in tests. I simply did not know whether the design would hold up, had to fit a lot of pieces together first. But now is a good time to put these tests in place.”

So often people talk about “Test First Development” that I think they’re insane, or just regurgitating marketing-speak to sound good. There are times when you’re coding things like SARAH where you don’t know how things are going to shake out that “Test First” just doesn’t make sense. If you know what you’re getting into when you’re coding, Test First sounds good, but when you’re exploring, “Oh, this is how SARAH should work”, or, “I thought an FTP server worked like this but it works like that”, Test First doesn’t make sense. (Once you understand the domain, giddyup, test your heart out.)