CODEWITHSUNDEEP
scala
Yaneeve
Yaneeve

Reputation: 4779

how to reference a specific function where two functions in scope have the same name

Given that we have two functions in scope with the same name but a different parameter list. How can I distinguish one from the other, such as in the case of trying to access the tupled function

Example:

scala> :paste
// Entering paste mode (ctrl-D to finish)


def f(s: String, l: Long): String = ???
def f(i: Int, l: Long): String = ???

val t:((String, Long)) => String = f.tupled

// Exiting paste mode, now interpreting.

<pastie>:15: error: ambiguous reference to overloaded definition,
both method f of type (i: Int, l: Long)String
and  method f of type (s: String, l: Long)String
match expected type ?
val t:((String, Long)) => String = f.tupled

Simplifying the problem to function literals yields:

scala> :paste
// Entering paste mode (ctrl-D to finish)

def f(i: Int, l: Long): String = ???
def f(s: String, l: Long): String = ???

val g = f _

// Exiting paste mode, now interpreting.

<pastie>:15: error: ambiguous reference to overloaded definition,
both method f of type (s: String, l: Long)String
and  method f of type (i: Int, l: Long)String
match expected type ?
val g = f _
        ^

But the explicit type annotation in the function literal example manages to solve the problem, where as for the apply method above in the context of tupled did not work

scala>

scala> :paste
// Entering paste mode (ctrl-D to finish)

def f(s: String, l: Long): String = ???
def f(i: Int, l: Long): String = ???

val g: (String, Long) => String  = f _

// Exiting paste mode, now interpreting.

f: (s: String, l: Long)String <and> (i: Int, l: Long)String
f: (s: String, l: Long)String <and> (i: Int, l: Long)String
g: (String, Long) => String = $$Lambda$1458/794413935@60cbba57

Upvotes: 0

Views: 60

Answers (2)

dyrkin
dyrkin

Reputation: 544

Here is the way you can achieve this

val t1 = (f(_: String, _: Long)).tupled
val t2 = (f(_: Int, _: Long)).tupled

output

t1: ((String, Long)) => String = scala.Function2$$Lambda$1188/922196321@3994b698
t2: ((Int, Long)) => String = scala.Function2$$Lambda$1188/922196321@4249db51

Upvotes: 3

Yaneeve
Yaneeve

Reputation: 4779

I found the following hack for the tupled problem:

scala> :paste
// Entering paste mode (ctrl-D to finish)

def f(s: String, l: Long): String = ???
def f(i: Int, l: Long): String = ???

val g: (String, Long) => String  = f _
val t = g.tupled

// Exiting paste mode, now interpreting.

f: (s: String, l: Long)String <and> (i: Int, l: Long)String
f: (s: String, l: Long)String <and> (i: Int, l: Long)String
g: (String, Long) => String = $$Lambda$1476/1981627424@172f2717
t: ((String, Long)) => String = scala.Function2$$Lambda$259/530042637@bda4cbe

Upvotes: 0

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