From d064763e9599f3ef4b7bccc1ed7d9df3687367ac Mon Sep 17 00:00:00 2001 From: Patrik Jansson Date: Thu, 9 Feb 2017 16:26:11 +0100 Subject: [PATCH] [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(-) 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.