Completely trivial, interpolation-only Templates; for when you want an API that fits on a business card. Text.Template.Inserts implements a subset of Mustache syntax. It uses template strings with named holes deliminted by "mustaches":

 import Data.HashMap.Strict as Map
 import Data.ByteString     as S

 context :: HashMap ByteString ByteString
 context = Map.fromList [ ("country", "Morocco")
                        , ("favoriteFruit", "bananas")
                        ]

>>> runTemplate (flip Map.lookup context) "I live in {{country}} and love {{favoriteFruit}}."
Right "I live in Morocco and love bananas"

>>> runTemplate (flip Map.lookup context) "My address is {{ address }}"
Left ["address"]

Text.Template.Inserts seeks to be as unsurprising and simple as possible sacrificing all kinds of niceities. Sometimes though, all you need is obvious, trivial string interpolation