A modern programming language that makes developers happier.

kotlinlang

Re-posting here for visibility:

&gt; Kotlin should automatically choose lambda expressions with a single argument over multiple arguments for the implicit case. You should not need to specify an explicit lambda signature in order to use `it` when competing overloads all have higher arity.

<https://github.com/kotlintest/kotlintest/pull/506#issuecomment-451624300>

What if there is an overload with a no-argument function type?

It is possible to disambiguate if the lambda references `it`, otherwise the language should prefer to use the function type with the fewest arguments.

Lambdas can be nested deep into each other, so to find out whether `it` is used, the compiler would have to analyze a lot of code.
And analyzing lambda bodies before completing overload resolution can hit exponential complexity in case of nested lambdas.

A good compromise would be to always choose the lowest arity (either nullary or unary) lambda that applies in a given context when lambda arguments are absent

Right now its impossible to call a 0-argument lambda if there are overloads with lambdas that have arguments