I am studying scala. For an practice, I am building a login page. To do this, I have been searched examples on web.
I found some interesting code like below.
val loginForm = Form(
tuple(
"username"->nonEmptyText,
"password"->nonEmptyText
)
)
I think after '->', it has to be an reserved words, right? I wonder how many reserved word can be in this place.
Especially some type like password. Any reference or example will be greatly welcomed :D
-> is actually just an operator to make creating a Tuple2 (or Pair) object easier. See the hairy details, for "how" such an operator can work across different types.
The normal/predef meaning of the -> operator is such that x -> y is equivalent to Tuple2(x, y), where y is just an expression. The code can then use any expression (reserved words or not) that is valid in the context.
In Play, note that nonEmptyText is itself just a value and does not involve any reserved words. Likewise, tuple is just a method for Play; see Handling form submission.
Predef.scala- github.com/scala/scala/blob/master/src/library/scala/… - where the->method and a lot of other interesting stuff is defined.TupleNdefined names, where N is, prior to Scala 2.11, a small (-ish) integer.