PureScript language preview

1. Module and a typed function

module header, a type signature, and a case expression

horizon-dark

module Main where

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

main :: Effect Unit
main = do
  let greeting = "Hello, " <> "world"
  case double 21 of
    42 -> log greeting
    _  -> log "nope"

atom-one-dark

module Main where

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

main :: Effect Unit
main = do
  let greeting = "Hello, " <> "world"
  case double 21 of
    42 -> log greeting
    _  -> log "nope"

github-dark

module Main where

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

main :: Effect Unit
main = do
  let greeting = "Hello, " <> "world"
  case double 21 of
    42 -> log greeting
    _  -> log "nope"

dracula

module Main where

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

main :: Effect Unit
main = do
  let greeting = "Hello, " <> "world"
  case double 21 of
    42 -> log greeting
    _  -> log "nope"

nord

module Main where

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

main :: Effect Unit
main = do
  let greeting = "Hello, " <> "world"
  case double 21 of
    42 -> log greeting
    _  -> log "nope"

github

module Main where

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

main :: Effect Unit
main = do
  let greeting = "Hello, " <> "world"
  case double 21 of
    42 -> log greeting
    _  -> log "nope"

2. Records and type classes

a record type, a type class, and an instance

horizon-dark

type Point = { x :: Number, y :: Number }

class Describable a where
  describe :: a -> String

instance describablePoint :: Describable Point where
  describe p = "(" <> show p.x <> ", " <> show p.y <> ")"

atom-one-dark

type Point = { x :: Number, y :: Number }

class Describable a where
  describe :: a -> String

instance describablePoint :: Describable Point where
  describe p = "(" <> show p.x <> ", " <> show p.y <> ")"

github-dark

type Point = { x :: Number, y :: Number }

class Describable a where
  describe :: a -> String

instance describablePoint :: Describable Point where
  describe p = "(" <> show p.x <> ", " <> show p.y <> ")"

dracula

type Point = { x :: Number, y :: Number }

class Describable a where
  describe :: a -> String

instance describablePoint :: Describable Point where
  describe p = "(" <> show p.x <> ", " <> show p.y <> ")"

nord

type Point = { x :: Number, y :: Number }

class Describable a where
  describe :: a -> String

instance describablePoint :: Describable Point where
  describe p = "(" <> show p.x <> ", " <> show p.y <> ")"

github

type Point = { x :: Number, y :: Number }

class Describable a where
  describe :: a -> String

instance describablePoint :: Describable Point where
  describe p = "(" <> show p.x <> ", " <> show p.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 -}
-}
double :: Int -> Int
double n = n + n

atom-one-dark

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

github-dark

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

dracula

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

nord

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

github

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