agda-spa/Showable.agda

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module Showable where
open import Data.String using (String; _++_)
open import Data.Nat using ()
open import Data.Nat.Show using () renaming (show to showNat)
open import Data.Fin using (Fin)
open import Data.Fin.Show using () renaming (show to showFin)
open import Data.Product using (_×_; _,_)
open import Data.Unit using (; tt)
record Showable {a} (A : Set a) : Set a where
field
show : A String
open Showable {{ ... }} public
instance
showableString : Showable String
showableString = record { show = λ s "\"" ++ s ++ "\"" }
showableNat : Showable
showableNat = record { show = showNat }
showableFin : {n : } Showable (Fin n)
showableFin = record { show = showFin }
showableProd : {a b} {A : Set a} {B : Set b}
{{ showableA : Showable A }} {{ showableB : Showable B }}
Showable (A × B)
showableProd {{ showableA }} {{ showableB }} = record
{ show = λ (a , b)
"(" ++ show a ++
", " ++ show b ++
")"
}
showableUnit : Showable
showableUnit = record { show = λ tt "()" }