__   __ __  __  ____   ___      _______________________________________________
||   || ||  || ||  || ||__      Hugs 98: Based on the Haskell 98 standard
||___|| ||__|| ||__||  __||     Copyright (c) 1994-2005
||---||         ___||           World Wide Web: http://haskell.org/hugs
||   ||                         Bugs: http://hackage.haskell.org/trac/hugs
||   || Version: Sep 2006       _______________________________________________

Haskell 98 mode: Restart with command line option -98 to enable extensions

Type :? for help
Main> :edit
Main> :r
Main> :edit
Main> :r
Main> makePairs []
[]
Main> makePairs [1,2,3,4]
[(1,2),(3,4)]
Main> makePairs [1,2]
[(1,2)]
Main> :r
Main> makePairs [1,2,3,4]
[(1,2),(3,4)]
Main> makePairs [1,2]
[(1,2)]
Main> :type makePairs
makePairs :: [a] -> [(a,a)]
Main> :r
ERROR file:{Hugs}\packages\hugsbase\Hugs.hs:26 - Type error in application
*** Expression     : (x1,x2) : makePairs xs
*** Term           : (x1,x2)
*** Type           : (a,a)
*** Does not match : a
*** Because        : unification would give infinite type

Prelude> :r
Main> :type makePairs
makePairs :: [a] -> [a]
Main> :r
Main> :type makePairs
makePairs :: [a] -> [(a,a)]
Main> :r
Main> :type makePairs
makePairs :: [a] -> [(a,a)]
Main> makePairs [2,2]
[(2,2)]
Main> makePairs [2]
[(2,2)]
Main> :r
Main> :type makePairs
makePairs :: Num a => [a] -> [(a,a)]
Main> :r
Main> :type makePairs
makePairs :: Num a => [b] -> [(b,a)]
Main> [ e | e <- [1,2,3,4], even e ]
[2,4]
Main> [ e | e <- [1,2,3,4] ]
[1,2,3,4]
Main> [ e | e <- [1,2,3,4], even e, e > 2 ]
[4]
Main> :r
Main> startsRight "hello"
False
Main> startsRight "belo"
True
Main> startsRight "b"
True
Main> startsRight "brad"
True
Main> [ s | s <- ["abc", "bcd", "def"], startsRight s ]
["bcd"]
Main> [ square s | s <- ["abc", "bcd", "def"], startsRight s ]
ERROR - Cannot infer instance
*** Instance   : Num [Char]
*** Expression : [ square s | s<-["abc","bcd","def"], startsRight s ]

Main> [ square e | e <- [1..10] ]
[1,4,9,16,25,36,49,64,81,100]
Main> [ square e | e <- [1..10], even e ]
[4,16,36,64,100]
Main> [ square e | e <- [1..10], even e ]
[4,16,36,64,100]
Main> [ x | x <- [ square e | e <- [1..10], even e ], x < 50 ]
[4,16,36]
Main> [ e | e <- [ square e | e <- [1..10], even e ], e< 50 ]
[4,16,36]
Main> [ (n,m) | n <- [1..10], m <- [20,30] ]
[(1,20),(1,30),(2,20),(2,30),(3,20),(3,30),(4,20),(4,30),(5,20),(5,30),(6,20),(6,30),(7,20),(7,30),(8,20),(8,30),(9,20),(9,30),(10,20),(10,30)]
Main> [ (n,m) | n <- [1..10], m <- [20,30], n*m < 20 ]
[]
Main> [ (n,m) | n <- [1..10], m <- [20,30], n*m < 80 ]
[(1,20),(1,30),(2,20),(2,30),(3,20)]
Main> 
Main> :r
Main> evens 20
[2,4,6,8,10,12,14,16,18,20]
Main> :r
Main> sumOfTriples [[1]]
[]
Main> sumOfTriples [[1,2,3]]
[6]
Main> sumOfTriples [[1,2,3], [2,3], [1,5,6]]
[6,12]
Main>