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Quiz for Creating F# List
f#

Hello, now that you are reading this post; then I will assume that you know how to create F# list. Now, take a look at the following options:

1)
let integers1 =
[ 1; 2; 3 ]

2)
let integers2 =
[ 1
2
3 ]

3)
let f x = x + 1
let integers3 =
[ f 1
f 2
f 3 ]

Which way(s) can successfully create an F# list? The answer is all of them (highlight to see the answer, but after you make a think). STOP TO THINK AND THEN GO ON WITH YOUR READING.

We all know the first one can do, but how about the others? Yesterday I came across the *strange* way to create F# list without ";" separator when I was reading <i>Expert F#<i>, but it seems there's no description about it within the language spec. Is it a new way to create F# list or an obsolete one? Thanks in advance!

.

Hi Allen,

Yes, this is correct. The indentation syntax allow you to write sequential elements without semi-colon separation. This applies to all semi-colon separated constructs in the language, e.g.

1
2
3
4
5
6
7
8

 

let f x =

    printfn "hello"   // note, no semicolon here

    printfn "world"

Also for records. The spec for the indentation syntax is available on the F# website.

Kind regards

Don

By on 7/9/2008 7:41 PM ()

Hi, don. Thanks for your quick response which makes things clear.

By on 7/9/2008 9:06 PM ()

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