{-
Transform each value in a `List` into `Text` and concatenate the result

Examples:

```
./concatMap Natural (λ(n : Natural) → "${Natural/show n} ") [ 0, 1, 2 ]
= "0 1 2 "

./concatMap Natural (λ(n : Natural) → "${Natural/show n} ") ([] : List Natural)
= ""
```
-}
    let concatMap
        : ∀(a : Type) → (a → Text) → List a → Text
        =   λ(a : Type)
          → λ(f : a → Text)
          → λ(xs : List a)
          → List/fold a xs Text (λ(x : a) → λ(y : Text) → f x ++ y) ""

in  concatMap