From f6b8b079b49a1fcfdc6143fc51bc5d3738ade8f0 Mon Sep 17 00:00:00 2001 From: Patrik Jansson Date: Fri, 23 Oct 2015 23:31:10 +0200 Subject: Some minor fixes I just noted that the example claiming that (add 10) is the same as (+10) was wrong. (A detail - it should be (10+) to match the argument order.) Then I just continued down making a few similar fixes and terminology updates. /Patrik PS. I've been teaching [Advanced Functional Programming](http://www.cse.chalmers.se/edu/course/afp/) (in Haskell) for a few years at Chalmers. --- haskell.html.markdown | 18 +++++++++--------- 1 file changed, 9 insertions(+), 9 deletions(-) (limited to 'haskell.html.markdown') diff --git a/haskell.html.markdown b/haskell.html.markdown index 08611e63..2f58b357 100644 --- a/haskell.html.markdown +++ b/haskell.html.markdown @@ -189,16 +189,16 @@ foo = add 10 -- foo is now a function that takes a number and adds 10 to it foo 5 -- 15 -- Another way to write the same thing -foo = (+10) +foo = (10+) foo 5 -- 15 -- function composition -- the (.) function chains functions together. -- For example, here foo is a function that takes a value. It adds 10 to it, -- multiplies the result of that by 4, and then returns the final value. -foo = (*4) . (+10) +foo = (4*) . (10+) --- (5 + 10) * 4 = 60 +-- 4*(10 + 5) = 60 foo 5 -- 60 -- fixing precedence @@ -222,7 +222,7 @@ even . fib $ 7 -- false -- 5. Type signatures ---------------------------------------------------- --- Haskell has a very strong type system, and everything has a type signature. +-- Haskell has a very strong type system, and every valid expression has a type. -- Some basic types: 5 :: Integer @@ -259,7 +259,7 @@ case args of _ -> putStrLn "bad args" -- Haskell doesn't have loops; it uses recursion instead. --- map applies a function over every element in an array +-- map applies a function over every element in a list map (*2) [1..5] -- [2, 4, 6, 8, 10] @@ -279,7 +279,7 @@ foldl (\x y -> 2*x + y) 4 [1,2,3] -- 43 -- This is the same as (2 * (2 * (2 * 4 + 1) + 2) + 3) --- foldl is left-handed, foldr is right- +-- foldl is left-handed, foldr is right-handed foldr (\x y -> 2*x + y) 4 [1,2,3] -- 16 -- This is now the same as @@ -318,7 +318,7 @@ Nothing -- of type `Maybe a` for any `a` -- it is not hard to explain enough to get going. -- When a Haskell program is executed, `main` is --- called. It must return a value of type `IO ()`. For example: +-- called. It must return a value of type `IO a` for some type `a`. For example: main :: IO () main = putStrLn $ "Hello, sky! " ++ (say Blue) @@ -361,7 +361,7 @@ sayHello = do -- You can think of a value of type `IO a` as representing a -- computer program that will generate a value of type `a` -- when executed (in addition to anything else it does). We can --- store and reuse this value using `<-`. We can also +-- name and reuse this value using `<-`. We can also -- make our own action of type `IO String`: action :: IO String @@ -417,7 +417,7 @@ Hello, Friend! There's a lot more to Haskell, including typeclasses and monads. These are the big ideas that make Haskell such fun to code in. I'll leave you with one final -Haskell example: an implementation of quicksort in Haskell: +Haskell example: an implementation of a quicksort variant in Haskell: ```haskell qsort [] = [] -- cgit v1.2.3 From d064763e9599f3ef4b7bccc1ed7d9df3687367ac Mon Sep 17 00:00:00 2001 From: Patrik Jansson Date: Thu, 9 Feb 2017 16:26:11 +0100 Subject: [haskell/en] some minor fixes (#2550) * [haskell/en] some minor fixes * Minor fixes after comments from @vendethiel --- haskell.html.markdown | 29 ++++++++++++++--------------- 1 file changed, 14 insertions(+), 15 deletions(-) (limited to 'haskell.html.markdown') diff --git a/haskell.html.markdown b/haskell.html.markdown index 4ce1a839..2b6aa2f7 100644 --- a/haskell.html.markdown +++ b/haskell.html.markdown @@ -68,7 +68,7 @@ not False -- True ---------------------------------------------------- -- Every element in a list must have the same type. --- These two lists are the same: +-- These two lists are equal: [1, 2, 3, 4, 5] [1..5] @@ -77,11 +77,11 @@ not False -- True -- You can create a step in a range. [0,2..10] -- [0, 2, 4, 6, 8, 10] -[5..1] -- This doesn't work because Haskell defaults to incrementing. +[5..1] -- [] (Haskell defaults to incrementing) [5,4..1] -- [5, 4, 3, 2, 1] -- indexing into a list -[1..10] !! 3 -- 4 +[1..10] !! 3 -- 4 (zero-based indexing) -- You can also have infinite lists in Haskell! [1..] -- a list of all the natural numbers @@ -152,8 +152,8 @@ fib x | otherwise = fib (x - 1) + fib (x - 2) -- Pattern matching is similar. Here we have given three different --- definitions for fib. Haskell will automatically call the first --- function that matches the pattern of the value. +-- equations for fib. Haskell will automatically use the first +-- equation whose left hand side pattern matches the value. fib 1 = 1 fib 2 = 2 fib x = fib (x - 1) + fib (x - 2) @@ -198,11 +198,11 @@ foo 5 -- 15 -- multiplies the result of that by 4, and then returns the final value. foo = (4*) . (10+) --- 4*(10 + 5) = 60 +-- 4*(10+ 5) = 60 foo 5 -- 60 -- fixing precedence --- Haskell has another operator called `$`. This operator applies a function +-- Haskell has an operator called `$`. This operator applies a function -- to a given parameter. In contrast to standard function application, which -- has highest possible priority of 10 and is left-associative, the `$` operator -- has priority of 0 and is right-associative. Such a low priority means that @@ -244,10 +244,10 @@ double x = x * 2 -- 6. Control Flow and If Expressions ---------------------------------------------------- --- if expressions +-- if-expressions haskell = if 1 == 1 then "awesome" else "awful" -- haskell = "awesome" --- if expressions can be on multiple lines too, indentation is important +-- if-expressions can be on multiple lines too, indentation is important haskell = if 1 == 1 then "awesome" else "awful" @@ -295,11 +295,10 @@ data Color = Red | Blue | Green -- Now you can use it in a function: - say :: Color -> String -say Red = "You are Red!" -say Blue = "You are Blue!" -say Green = "You are Green!" +say Red = "You are Red!" +say Blue = "You are Blue!" +say Green = "You are Green!" -- Your data types can have parameters too: @@ -384,8 +383,8 @@ main'' = do -- The type `IO` is an example of a "monad". The way Haskell uses a monad to -- do IO allows it to be a purely functional language. Any function that -- interacts with the outside world (i.e. does IO) gets marked as `IO` in its --- type signature. This lets us reason about what functions are "pure" (don't --- interact with the outside world or modify state) and what functions aren't. +-- type signature. This lets us reason about which functions are "pure" (don't +-- interact with the outside world or modify state) and which functions aren't. -- This is a powerful feature, because it's easy to run pure functions -- concurrently; so, concurrency in Haskell is very easy. -- cgit v1.2.3 From 0a0080a955c11c9b29757d20c74412e6ced67f16 Mon Sep 17 00:00:00 2001 From: ven Date: Thu, 9 Feb 2017 16:27:29 +0100 Subject: #2550 --- haskell.html.markdown | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'haskell.html.markdown') diff --git a/haskell.html.markdown b/haskell.html.markdown index 2b6aa2f7..ce804415 100644 --- a/haskell.html.markdown +++ b/haskell.html.markdown @@ -152,7 +152,7 @@ fib x | otherwise = fib (x - 1) + fib (x - 2) -- Pattern matching is similar. Here we have given three different --- equations for fib. Haskell will automatically use the first +-- equations that define fib. Haskell will automatically use the first -- equation whose left hand side pattern matches the value. fib 1 = 1 fib 2 = 2 @@ -198,7 +198,7 @@ foo 5 -- 15 -- multiplies the result of that by 4, and then returns the final value. foo = (4*) . (10+) --- 4*(10+ 5) = 60 +-- 4*(10+5) = 60 foo 5 -- 60 -- fixing precedence -- cgit v1.2.3 From 63a6eb1182205389388e13b680962199ac9b3ffb Mon Sep 17 00:00:00 2001 From: Andy Date: Sat, 1 Apr 2017 22:19:58 +0200 Subject: [haskell] Updating second headline (#2695) * Haskell: Updating second headline * Haskell: Updating second headline (es) * Haskell: Updating second headline (fr) * Haskell: Updating second headline (pl) * Haskell: Updating second headline (pt) * Haskell: Updating second headline (ro) * Haskell: Updating second headline (ru) * Haskell: Updating second headline (cn) --- haskell.html.markdown | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'haskell.html.markdown') diff --git a/haskell.html.markdown b/haskell.html.markdown index ce804415..4e254070 100644 --- a/haskell.html.markdown +++ b/haskell.html.markdown @@ -64,7 +64,7 @@ not False -- True ---------------------------------------------------- --- Lists and Tuples +-- 2. Lists and Tuples ---------------------------------------------------- -- Every element in a list must have the same type. -- cgit v1.2.3