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question on the colon operator
f#

I typed something into fsi and but can't explain the result:

first:

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> 1:int;;
val it : int = 1
> val it : (int -> int) = <fun:it@28>

and then:
> 1:2;;
val it : int = 1
> val it : int = 2

In the first case I expect the the :int type annotation to be redundant, so where does the int->int function come from?

In the second case I wonder why I could write a integer where a type is expected.

.

strange. I get a different result:

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> 1:int;;

  1:int;;
  -^^

stdin(2,1): error FS0191: syntax error.
> val it : (int -> int) = <fun:it@2>

using brackets helps so:

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> (1:int);;
val it : int = 1

regards,

Danny

By on 8/27/2008 3:44 AM ()

In this case FSI is recovering from a syntax error and continuing to process input. This behaviour will be corrected to stop-on-first-error in the F# September CTP release, which will be out soon.

In the first example, the "1:" causes a syntax error, since type-annotated expressions need parentheses at the top level. The remainder of the expression is "int", which is a library-defined function for converting things to integers.

Don

By on 8/28/2008 5:05 PM ()

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