Question

I’m looking for something akin to the dict/list/set comprehensions in Python. In Python you can do:

[x+2 for x in list if x > 10]

and in F#

[for x in list do if x > 10 yield x+2]

but in Python, you can also do:

{x+2 for x in list if x > 10}

to generate Sets, and

{k: (v+10)/2 for k, v in list.items() if k > 5}

to generate Dicts. Is there any equivalent (both in terms of function and in terms of overall tidyness) syntax for this sort of thing in F#?

Answer 1

There is a set function accepting seq<_>, so you can do:

set [for x in list do if x > 10 yield x+2]

Same with dict. Here are the relevant docs:

set: http://msdn.microsoft.com/en-us/library/ee353747.aspx
dict: http://msdn.microsoft.com/en-us/library/ee353774.aspx