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90 lines
2.3 KiB
Markdown
90 lines
2.3 KiB
Markdown
# 🦓🦒Okapi
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Okapi is a data-driven micro framework for implementing HTTP servers.
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- Ergonomic DSLs for routing and parsing requests
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- Integrate Okapi with ANY monad stack or effect system
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- Automatically generate clients and OpenAPI specifications (coming soon)
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- Programatically generate your API's structure
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## Hello World Example
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```haskell
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helloWorld =
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responder @200 @'[] @Text.Text @Text.Text
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. method HTTP.GET id
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$ \greet _req -> return $ greet noHeaders "Hello World!"
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main =
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Warp.run 8000
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. withDefault helloWorld
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$ \_ resp -> resp $ Wai.responseLBS HTTP.status404 [] "Not Found..."
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```
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## Calculator Example
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```haskell
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data Operator
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= Add
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| Sub
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| Mul
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| Div
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| Sq
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| Neg
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deriving (Show)
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instance Web.FromHttpApiData Operator where
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parseUrlPiece "add" = Right Add
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parseUrlPiece "sub" = Right Sub
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parseUrlPiece "minus" = Right Sub
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parseUrlPiece "mul" = Right Mul
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parseUrlPiece "div" = Right Div
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parseUrlPiece "neg" = Right Neg
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parseUrlPiece "sq" = Right Sq
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parseUrlPiece "square" = Right Sq
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parseUrlPiece _ = Left "Can't parse operator..."
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shared =
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lit "calc"
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. param @Operator
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. param @Int
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unary =
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responder @200 @'[] @Text.Text @Int
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. responder @500 @'[] @Text.Text @Text.Text
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. method HTTP.GET id
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unaryHandler operator x ok wrongArgs _req =
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return $ case operator of
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Sq -> ok noHeaders (x * x)
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Neg -> ok noHeaders (x * (-1))
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_ -> wrongArgs noHeaders $ Text.pack (show operator) <> " needs two arguments."
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binary =
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param @Int
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. responder @200 @'[] @Text.Text @Int
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. responder @500 @'[] @Text.Text @Text.Text
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. responder @403 @'[] @Text.Text @Text.Text
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. method HTTP.GET id
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binaryHandler operator x y ok wrongArgs divByZeroErr _req =
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return $ case operator of
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Add -> ok noHeaders (x + y)
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Sub -> ok noHeaders (x - y)
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Mul -> ok noHeaders (x * y)
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Div ->
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if y == 0
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then divByZeroErr noHeaders "You can't divide by 0."
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else ok noHeaders (div x y)
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_ -> wrongArgs noHeaders $ Text.pack (show operator) <> " needs one argument."
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calc = shared $ choice
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[ unary unaryHandler
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, binary binaryHandler
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]
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main =
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Warp.run 8003
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. withDefault calc
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$ \_ resp -> resp $ Wai.responseLBS HTTP.status404 [] "Not Found..."
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``` |