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elm

How do you print a List in Elm?

How do I convert a value of type List to a String in Elm?

Basically I'm looking for a function with the signature a -> String or List -> String.

Example

Let's say I have a function intAverage:

intAverage l = case l of
  [] -> 0
  otherwise -> Debug.log (<<SHOW_FUNCTION>> l) (List.sum l // List.length l)

Here I want to inspect the list, in order to understand what's being passed to my function. Debug.log expects a String which makes me look for a function with the signature a -> String or List -> String but I have been unsuccessful in finding such a function in the Elm package docs.

Haskell has Debug.traceShow (which is simply an application of the function show on the first argument of Debug.trace) but I can't find the equivalent in Elm.

Solution

  • On Elm 0.19, it's been moved to Debug.toString:

    For example:

    > Debug.toString [1,2,3]
"[1,2,3]" : String