```haskell
{-
Haskell Server Pages are a nice way to create server responses.
You call them from your parsers like so:
hsp
:: FilePath
-> m Response
hsp rootDir = undefined
main :: IO
main = run id (hsp "/")
Will look for `.hsp` files in the root directory and serve them according to their path relative to the root directory.
home.hsp -> /home
users.hsp -> /users
users
|- userID::Int.hsp -> /user/userID::Int
|- userID::Int
|- posts.hsp -> /user/userID::Int/posts
|- follows.hsp -> /user/userID::Int/follows
This whole module is an example HSP.
-}
-- /store/category::Category
methodGET
mbColor <- optional $ queryParam @Color "color"
mbBrand <- optional $ queryParam @Brand "brand"
mbMinPrice <- optional $ queryParam @Float "min_price"
mbMaxPrice <- optional $ queryParam @Float "max_price"
products <- select conn do
each product
where_ ...
case category of
Shoes -> Shoes on SALE!
Shirts ->
Dresses -> Beautiful DRESSES For SALE! Red Dresses 25% OFF!
Pants ->
for_ products \Product{..} ->
Forever51 Clothing Store
<%= productName %>
<%= footer %>
```