Idris language preview

1. Module and a total function

module header, a type signature, and a case expression

horizon-dark

module Main

total
double : Int -> Int
double n = n + n

main : IO ()
main = do
  let greeting = "Hello, " ++ "world"
  case double 21 of
       42 => putStrLn greeting
       _  => putStrLn "nope"

atom-one-dark

module Main

total
double : Int -> Int
double n = n + n

main : IO ()
main = do
  let greeting = "Hello, " ++ "world"
  case double 21 of
       42 => putStrLn greeting
       _  => putStrLn "nope"

github-dark

module Main

total
double : Int -> Int
double n = n + n

main : IO ()
main = do
  let greeting = "Hello, " ++ "world"
  case double 21 of
       42 => putStrLn greeting
       _  => putStrLn "nope"

dracula

module Main

total
double : Int -> Int
double n = n + n

main : IO ()
main = do
  let greeting = "Hello, " ++ "world"
  case double 21 of
       42 => putStrLn greeting
       _  => putStrLn "nope"

nord

module Main

total
double : Int -> Int
double n = n + n

main : IO ()
main = do
  let greeting = "Hello, " ++ "world"
  case double 21 of
       42 => putStrLn greeting
       _  => putStrLn "nope"

github

module Main

total
double : Int -> Int
double n = n + n

main : IO ()
main = do
  let greeting = "Hello, " ++ "world"
  case double 21 of
       42 => putStrLn greeting
       _  => putStrLn "nope"

2. Records and interfaces

a record type, an interface, and an implementation

horizon-dark

record Point where
  constructor MkPoint
  x, y : Int

interface Describable a where
  describe : a -> String

implementation Describable Point where
  describe (MkPoint x y) = "(" ++ show x ++ ", " ++ show y ++ ")"

atom-one-dark

record Point where
  constructor MkPoint
  x, y : Int

interface Describable a where
  describe : a -> String

implementation Describable Point where
  describe (MkPoint x y) = "(" ++ show x ++ ", " ++ show y ++ ")"

github-dark

record Point where
  constructor MkPoint
  x, y : Int

interface Describable a where
  describe : a -> String

implementation Describable Point where
  describe (MkPoint x y) = "(" ++ show x ++ ", " ++ show y ++ ")"

dracula

record Point where
  constructor MkPoint
  x, y : Int

interface Describable a where
  describe : a -> String

implementation Describable Point where
  describe (MkPoint x y) = "(" ++ show x ++ ", " ++ show y ++ ")"

nord

record Point where
  constructor MkPoint
  x, y : Int

interface Describable a where
  describe : a -> String

implementation Describable Point where
  describe (MkPoint x y) = "(" ++ show x ++ ", " ++ show y ++ ")"

github

record Point where
  constructor MkPoint
  x, y : Int

interface Describable a where
  describe : a -> String

implementation Describable Point where
  describe (MkPoint x y) = "(" ++ show x ++ ", " ++ show y ++ ")"

3. Nested comments

a doc comment wrapping an example that has its own comment

horizon-dark

{- computes the double of a number
   {- example: double 21 == 42 -}
-}
total
double : Int -> Int
double n = n + n

atom-one-dark

{- computes the double of a number
   {- example: double 21 == 42 -}
-}
total
double : Int -> Int
double n = n + n

github-dark

{- computes the double of a number
   {- example: double 21 == 42 -}
-}
total
double : Int -> Int
double n = n + n

dracula

{- computes the double of a number
   {- example: double 21 == 42 -}
-}
total
double : Int -> Int
double n = n + n

nord

{- computes the double of a number
   {- example: double 21 == 42 -}
-}
total
double : Int -> Int
double n = n + n

github

{- computes the double of a number
   {- example: double 21 == 42 -}
-}
total
double : Int -> Int
double n = n + n