updated purescript example for compiler version >= 0.7.4.1

purescript.html.markdown

@@ -2,194 +2,207 @@
 language: purescript
 contributors:
     - ["Fredrik Dyrkell", "http://www.lexicallyscoped.com"]
+    - ["Thimoteus", "https://github.com/Thimoteus"]
 ---
 
 PureScript is a small strongly, statically typed language compiling to Javascript.
 
 * Learn more at [http://www.purescript.org/](http://www.purescript.org/)
-* Documentation: [http://docs.purescript.org/en/latest/](http://docs.purescript.org/en/latest/)
+* Documentation: [http://pursuit.purescript.org/](http://pursuit.purescript.org/)
 * Book: Purescript by Example, [https://leanpub.com/purescript/](https://leanpub.com/purescript/)
 
-```haskell
+```purescript
 
 --
 -- 1. Primitive datatypes that corresponds to their Javascript
 -- equivalents at runtime.
 
+> import Prelude
 -- Numbers
-1 + 7*5 :: Number -- 36
+> 1.0 + 7.2*5.5 :: Number -- 40.6
+-- Ints
+> 1 + 2*5 :: Int -- 11
 -- Types are inferred, so the following works fine
-9 / 2.5 + 4.4 -- 8
+> 9.0/2.5 + 4.4 -- 8.0
+-- But Ints and Numbers don't mix, so the following won't
+> 5/2 + 2.5 -- Expression 2.5 does not have type Int
 -- Hexadecimal literals
-0xff + 1 -- 256
+> 0xff + 1 -- 256
 -- Unary negation
-6 * -3 -- -18
+> 6 * -3 -- -18
-6 * negate 3 -- -18
+> 6 * negate 3 -- -18
--- Modulus
+-- Modulus, from purescript-math (Math)
-3 % 2 -- 1
+> 3.0 % 2.0 -- 1.0
-4 % 2 -- 0
+> 4.0 % 2.0 -- 0.0
 -- Inspect the type of an expression in psci
-:t 9 / 2.5 + 4.4 -- Prim.Number
+> :t 9.5/2.5 + 4.4 -- Prim.Number
 
 -- Booleans
-true :: Boolean -- true
+> true :: Boolean -- true
-false :: Boolean -- false
+> false :: Boolean -- false
 -- Negation
-not true --false
+> not true -- false
-23 == 23 -- true
+> 23 == 23 -- true
-1 /= 4 -- true
+> 1 /= 4 -- true
-1 >= 4 -- false
+> 1 >= 4 -- false
 -- Comparisions < <= > >=
 -- are defined in terms of compare
-compare 1 2 -- LT
+> compare 1 2 -- LT
-compare 2 2 -- EQ
+> compare 2 2 -- EQ
-compare 3 2 -- GT
+> compare 3 2 -- GT
 -- Conjunction and Disjunction
-true && (9 >= 19 || 1 < 2) -- true
+> true && (9 >= 19 || 1 < 2) -- true
 
 -- Strings
-"Hellow" :: String -- "Hellow"
+> "Hellow" :: String -- "Hellow"
--- Multiline string
+-- Multiline string without newlines, to run in psci use the --multi-line-mode flag
-"Hellow\
+> "Hellow\
 \orld" -- "Helloworld"
+-- Multiline string with newlines
+> """Hello 
+world""" -- "Hello\nworld"
 -- Concatenate
-"such " ++ "amaze" -- "such amaze"
+> "such " ++ "amaze" -- "such amaze"
 
 --
 -- 2. Arrays are Javascript arrays, but must be homogeneous
 
-[1,1,2,3,5,8] :: [Number] -- [1,1,2,3,5,8]
+> [1,1,2,3,5,8] :: Array Number -- [1,1,2,3,5,8]
-[true, true, false] :: [Boolean] -- [true,true,false]
+> [true, true, false] :: Array Boolean -- [true,true,false]
 -- [1,2, true, "false"] won't work
--- `Cannot unify Prim.Number with Prim.Boolean`
+-- `Cannot unify Prim.Int with Prim.Boolean`
 -- Cons (prepend)
-1 : [2,4,3] -- [1,2,4,3]
+> 1 : [2,4,3] -- [1,2,4,3]
 
 -- Requires purescript-arrays (Data.Array)
 -- and purescript-maybe (Data.Maybe)
 
 -- Safe access return Maybe a
-head [1,2,3] -- Just (1)
+> head [1,2,3] -- Just (1)
-tail [3,2,1] -- Just ([2,1])
+> tail [3,2,1] -- Just ([2,1])
-init [1,2,3] -- Just ([1,2])
+> init [1,2,3] -- Just ([1,2])
-last [3,2,1] -- Just (1)
+> last [3,2,1] -- Just (1)
 -- Random access - indexing
-[3,4,5,6,7] !! 2 -- Just (5)
+> [3,4,5,6,7] !! 2 -- Just (5)
 -- Range
-1..5 -- [1,2,3,4,5]
+> 1..5 -- [1,2,3,4,5]
-length [2,2,2] -- 3
+> length [2,2,2] -- 3
-drop 3 [5,4,3,2,1] -- [2,1]
+> drop 3 [5,4,3,2,1] -- [2,1]
-take 3 [5,4,3,2,1] -- [5,4,3]
+> take 3 [5,4,3,2,1] -- [5,4,3]
-append [1,2,3] [4,5,6] -- [1,2,3,4,5,6]
+> append [1,2,3] [4,5,6] -- [1,2,3,4,5,6]
 
 --
 -- 3. Records are Javascript objects, with zero or more fields, which
--- can have different types
+-- can have different types.
-let book = {title: "Foucault's pendulum", author: "Umberto Eco"}
+-- In psci you have to write `let` in front of the function to get a
+-- top level binding.
+> let book = {title: "Foucault's pendulum", author: "Umberto Eco"}
 -- Access properties
-book.title -- "Foucault's pendulum"
+> book.title -- "Foucault's pendulum"
 
-getTitle b = b.title
+> let getTitle b = b.title
 -- Works on all records with a title (but doesn't require any other field)
-getTitle book -- "Foucault's pendulum"
+> getTitle book -- "Foucault's pendulum"
-getTitle {title: "Weekend in Monaco", artist: "The Rippingtons"} -- "Weekend in Monaco"
+> getTitle {title: "Weekend in Monaco", artist: "The Rippingtons"} -- "Weekend in Monaco"
+-- Can use underscores as shorthand
+> _.title book -- "Foucault's pendulum"
 -- Update a record
-changeTitle b t = b {title = t}
+> let changeTitle b t = b {title = t}
-changeTitle book "Ill nome della rosa" -- {title: "Ill nome della
+> getTitle (changeTitle book "Ill nome della rosa") -- "Ill nome della rosa"
-  -- rosa", author: "Umberto Eco"}
 
 --
 -- 4. Functions
-sumOfSquares x y = x*x+y*y
+-- In psci's multiline mode
-sumOfSquares 3 4 -- 25
+> let sumOfSquares :: Int -> Int -> Int
--- In psci you have to write `let` in front of the function to get a
+      sumOfSquares x y = x*x + y*y
--- top level binding
+> sumOfSquares 3 4 -- 25
-mod x y = x % y
+> let myMod x y = x % y
-mod 3 2 -- 1
+> myMod 3.0 2.0 -- 1.0
 -- Infix application of function
-3 `mod` 2 -- 1
+> 3 `mod` 2 -- 1
 
--- function application have higher precedence than all other
+-- function application has higher precedence than all other
 -- operators
-sumOfSquares 3 4 * sumOfSquares 4 5 -- 1025
+> sumOfSquares 3 4 * sumOfSquares 4 5 -- 1025
 
 -- Conditional
-abs' n = if n>=0 then n else -n
+> let abs' n = if n>=0 then n else -n
-abs' (-3) -- 3
+> abs' (-3) -- 3
 
 -- Guarded equations
-abs n | n >= 0    = n
+> let abs'' n | n >= 0    = n
-      | otherwise = -n
+              | otherwise = -n
 
 -- Pattern matching
 
--- Note the type signature, input is an array of numbers The pattern
+-- Note the type signature, input is a list of numbers. The pattern matching
--- matching destructures and binds the array into parts
+-- destructures and binds the list into parts.
-first :: [Number] -> Number
+-- Requires purescript-lists (Data.List)
-first (x:_) = x
+> let first :: forall a. List a -> a
-first [3,4,5] -- 3
+      first (Cons x _) = x
-second :: [Number] -> Number
+> first (toList [3,4,5]) -- 3
-second (_:y:_) = y
+> let second :: forall a. List a -> a
-second [3,4,5] -- 4
+      second (Cons _ (Cons y _)) = y
-sumTwo :: [Number] -> [Number]
+> second (toList [3,4,5]) -- 4
-sumTwo (x:y:rest) = (x+y) : rest
+> let sumTwo :: List Int -> List Int
-sumTwo [2,3,4,5,6] -- [5,4,5,6]
+      sumTwo (Cons x (Cons y rest)) = x + y : rest
+> fromList (sumTwo (toList [2,3,4,5,6])) :: Array Int -- [5,4,5,6]
 
--- sumTwo doesn't handle when the array is empty or just have one
+-- sumTwo doesn't handle when the list is empty or there's only one element in
--- element in which case you get an error
+-- which case you get an error.
 sumTwo [1] -- Failed pattern match
 
 -- Complementing patterns to match
 -- Good ol' Fibonacci
-fib 1 = 1
+> let fib 1 = 1
-fib 2 = 2
+      fib 2 = 2
-fib x = fib (x-1) + fib (x-2)
+      fib x = fib (x-1) + fib (x-2)
-fib 10 -- 89
+> fib 10 -- 89
 
 -- Use underscore to match any, where you don't care about the binding name
-isZero 0 = true
+> let isZero 0 = true
-isZero _ = false
+      isZero _ = false
 
 -- Pattern matching on records
-ecoTitle {author = "Umberto Eco", title = t} = Just t
+> let ecoTitle {author = "Umberto Eco", title = t} = Just t
-ecoTitle _ = Nothing
+      ecoTitle _ = Nothing
 
-ecoTitle book -- Just ("Foucault's pendulum")
+> ecoTitle book -- Just ("Foucault's pendulum")
-ecoTitle {title: "The Quantum Thief", author: "Hannu Rajaniemi"} -- Nothing
+> ecoTitle {title: "The Quantum Thief", author: "Hannu Rajaniemi"} -- Nothing
 -- ecoTitle requires both field to type check:
-ecoTitle {title: "The Quantum Thief"} -- Object does not have property author
+> ecoTitle {title: "The Quantum Thief"} -- Object lacks required property "author"
 
 -- Lambda expressions
-(\x -> x*x) 3 -- 9
+> (\x -> x*x) 3 -- 9
-(\x y -> x*x + y*y) 4 5 -- 41
+> (\x y -> x*x + y*y) 4 5 -- 41
-sqr = \x -> x*x
+> let sqr = \x -> x*x
 
 -- Currying
-add x y = x + y -- is equivalent with
+> let myAdd x y = x + y -- is equivalent with
-add = \x -> (\y -> x+y)
+> let myAdd' = \x -> \y -> x + y
-add3 = add 3
+> let add3 = myAdd 3
-:t add3 -- Prim.Number -> Prim.Number
+> :t add3 -- Prim.Int -> Prim.Int
 
 -- Forward and backward function composition
 -- drop 3 followed by taking 5
-(drop 3 >>> take 5) (1..20) -- [4,5,6,7,8]
+> (drop 3 >>> take 5) (1..20) -- [4,5,6,7,8]
 -- take 5 followed by dropping 3
-(drop 3 <<< take 5) (1..20) -- [4,5]
+> (drop 3 <<< take 5) (1..20) -- [4,5]
 
 -- Operations using higher order functions
-even x = x % 2 == 0
+> let even x = x `mod` 2 == 0
-filter even (1..10) -- [2,4,6,8,10]
+> filter even (1..10) -- [2,4,6,8,10]
-map (\x -> x+11) (1..5) -- [12,13,14,15,16]
+> map (\x -> x + 11) (1..5) -- [12,13,14,15,16]
 
 -- Requires purescript-foldable-traversabe (Data.Foldable)
 
-foldr (+) 0 (1..10) -- 55
+> foldr (+) 0 (1..10) -- 55
-sum (1..10) -- 55
+> sum (1..10) -- 55
-product (1..10) -- 3628800
+> product (1..10) -- 3628800
 
 -- Testing with predicate
-any even [1,2,3] -- true
+> any even [1,2,3] -- true
-all even [1,2,3] -- false
+> all even [1,2,3] -- false
 
 ```