How do you say `\\x -> y`? [closed]

问题:

How is the expression \x -> y typically pronounced by Haskell programmers?

I ask because I ordinarily say "lambda eks dot why," because it's written λx.y in a general context and I was introduced to the lambda calculus through books and notes, without hearing anyone translate the terms into speech. But it's an arrow, not a dot, in Haskell.

I understand that computer-science people often elide the dot in speech ("lambda eks [short pause] y"). F# and C# programmers, the web tells me, often pronounce the equivalent expression x => y as "eks goes to why." I don't know how similar constructions are said in other contexts.

So among Haskellers is it "lambda eks arrow why," or what?

回答1:

I usually pronounce it as "lambda x to y". This is very short and matches how you would type it in TeX: \lambda x \to y. (As a cute note, I have a TeX input mode in my editor, so I could type the above to get λ x → y. :P)

That said, I'm sure that everyone would understand you if you said "lambda x dot y"--most people are at least familiar with that notation and the it's very easy to guess what you mean from context.

I've never heard anybody say "goes to", however.

回答2:

Answering for myself: in my mind I often say it as "x goes to y", or simply "x to y" -- but I think it adapts a bit for some common higher order functions. If you had map (\x -> (x * 2) - 1) foo, I'd think of it as "map x to x times two minus one on foo". However, for something like filter (\x -> x /= 6) foo I'd read it as "filter x, x doesn't equal 6, on foo" -- effectively, the arrow becomes a comma in that case.