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Merge pull request #3157 from alexgrejuc/master

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[haskell/en] tweaked tuple information to demonstrate wildcards and a more useful tuple function
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Adam Bard
2018-09-08 09:48:48 -07:00
committed by GitHub
parent e6c27bb820 d063ea6469
commit e6b01188bf
1 changed files with 10 additions and 7 deletions
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@@ -124,6 +124,9 @@ last [1..5] -- 5
fst ("haskell", 1) -- "haskell" fst ("haskell", 1) -- "haskell"
snd ("haskell", 1) -- 1 snd ("haskell", 1) -- 1
-- pair element accessing does not work on n-tuples (i.e. triple, quadruple, etc)
snd ("snd", "can't touch this", "da na na na") -- error! see function below
---------------------------------------------------- ----------------------------------------------------
-- 3. Functions -- 3. Functions
---------------------------------------------------- ----------------------------------------------------
@@ -159,8 +162,8 @@ 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)
-- Pattern matching on tuples: -- Pattern matching on tuples
foo (x, y) = (x + 1, y + 2) sndOfTriple (_, y, _) = y -- use a wild card (_) to bypass naming unused value
-- Pattern matching on lists. Here `x` is the first element -- Pattern matching on lists. Here `x` is the first element
-- in the list, and `xs` is the rest of the list. We can write -- in the list, and `xs` is the rest of the list. We can write
@@ -207,7 +210,7 @@ foo 5 -- 60
-- to a given parameter. In contrast to standard function application, which -- to a given parameter. In contrast to standard function application, which
-- has highest possible priority of 10 and is left-associative, the `$` operator -- has highest possible priority of 10 and is left-associative, the `$` operator
-- has priority of 0 and is right-associative. Such a low priority means that -- has priority of 0 and is right-associative. Such a low priority means that
-- the expression on its right is applied as the parameter to the function on its left. -- the expression on its right is applied as a parameter to the function on its left.
-- before -- before
even (fib 7) -- false even (fib 7) -- false