# Function signatures

**URL:** <https://discourse.elm-lang.org/t/function-signatures/3337>\
**Category:** Learn\
**Created:** [March 16, 2019, 7:18am UTC](https://discourse.elm-lang.org/t/function-signatures/3337 "2019-03-16T07:18:04Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Jakob\_Moller](https://yyz1.discourse-cdn.com/flex035/user_avatar/discourse.elm-lang.org/jakob_moller/32/1916_2.png) [@Jakob\_Moller](https://discourse.elm-lang.org/u/Jakob_Moller)\
**Post date:** [March 16, 2019, 7:18am UTC](https://discourse.elm-lang.org/t/function-signatures/3337/1 "2019-03-16T07:18:04Z")

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In [https://package.elm-lang.org/packages/elm/core/latest/Basics](https://package.elm-lang.org/packages/elm/core/latest/Basics) addition is documented with the following signature:

(+) : number -\> number -\> number

I would expect that partial application is possible, but it is not - you have to provide both arguments. In my mind the signature should be something like:

(+) : (number, number) -\> number

Am I wrong?

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<div class="post-metadata">

**Author:** ![dta](https://yyz1.discourse-cdn.com/flex035/user_avatar/discourse.elm-lang.org/dta/32/1917_2.png) [@dta](https://discourse.elm-lang.org/u/dta)\
**Post date:** [March 16, 2019, 8:18am UTC](https://discourse.elm-lang.org/t/function-signatures/3337/2 "2019-03-16T08:18:07Z")

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Putting an infix operator in parentheses makes it act like a normal function, so

```auto
addFive : number -> number
addFive = (+) 5

```

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<div class="post-metadata">

**Author:** ![system](https://canada1.discourse-cdn.com/flex035/uploads/elm_lang/original/1X/50a05e53677a2c3b47776d7abd0f113eb50193a1.png) [@system](https://discourse.elm-lang.org/u/system)\
**Post date:** [March 26, 2019, 8:18am UTC](https://discourse.elm-lang.org/t/function-signatures/3337/3 "2019-03-26T08:18:09Z")

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