There's a 'powerset' thread on this list [1][2] starting 4th June which I think contains some of the answers you seek. Read and you shall learn! #g -- [1] List archive: http://www.haskell.org/pipermail/haskell-cafe/ [2] Powerset thread starts: http://www.haskell.org/pipermail/haskell-cafe/2003-June/004463.html (Read into the thread, because there are some problems with the code that appears earlier in the thread.) At 22:55 19/07/03 -0300, Douglas O. Matoso wrote:
Hi,
I have an school assignment that asks to implement an truth table of propositional formulas. I'm having difficulties in the following part:
data Prop = Var Char | Not Prop | And Prop Prop | Or Prop Prop type Subst = [(Char,Bool)]
- Define a function bools :: Int -> [[Bool]] that calculates all possible lists of logical values of a specific length. For example, bools 2 should give the following list: [[False,False], [False,True ], [True ,False], [True ,True ]]
- Define a function substs :: Prop -> [Subst] that calculates all possible substitutions for the variables of a proposition.
For example, substs p2 should give the following list: [[('A',False),('B',False)], [('A',False),('B',True) ], [('A',True) ,('B',False)], [('A',True) ,('B',True) ]]
I would be thankful for any help.
Douglas Matoso
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