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added info about tuples, integrated wild card use into a function definition

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Alex Grejuc 2018-07-10 15:12:23 -07:00
parent 0d211d3419
commit 8c30522d58
1 changed files with 9 additions and 6 deletions
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haskell.html.markdown
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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 to get around this
---------------------------------------------------- ----------------------------------------------------
-- 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, using wild card (_) to bypass naming an unused value
foo (x, y) = (x + 1, y + 2) sndOfTriple (_, y, _) = y
-- 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
@ -203,9 +206,9 @@ foo = (4*) . (10+)
foo 5 -- 60 foo 5 -- 60
-- fixing precedence -- fixing precedence
-- Haskell has an 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 -- 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 the parameter to the function on its left.
@ -223,7 +226,7 @@ even . fib $ 7 -- false
-- 5. Type signatures -- 5. Type signatures
---------------------------------------------------- ----------------------------------------------------
-- Haskell has a very strong type system, and every valid expression has a type. -- Haskell has a very strong type system, and every valid expression has a type.
-- Some basic types: -- Some basic types:
5 :: Integer 5 :: Integer