Difference between revisions of "FP Laboratory 2"
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| Line 21: | Line 21: | ||
odd 3 | odd 3 | ||
</syntaxhighlight> | </syntaxhighlight> | ||
| − | * At presentations, we have spoken about some basic types: <code> Int, Double, Bool, Char</code>. For each of previous expressions assign them the most appropriate of these basic data types. You can verify your guess by using <code>::</code>. For example, for the first expression, | + | * At presentations, we have spoken about some basic types: <code> Int, Double, Bool, Char</code>. For each of previous expressions assign them the most appropriate of these basic data types. You can verify your guess by using <code>::</code>. For example, for the first expression, let's assume it is <code>Int</code>. We can cast the result to integer and get the following result. |
<syntaxhighlight lang="Haskell" class="myDark" > | <syntaxhighlight lang="Haskell" class="myDark" > | ||
Prelude> :type (5 + 8) :: Int | Prelude> :type (5 + 8) :: Int | ||
| Line 34: | Line 34: | ||
* In the expression: (5 + 8) :: Char | * In the expression: (5 + 8) :: Char | ||
</syntaxhighlight> | </syntaxhighlight> | ||
| − | For this | + | For this expression, also the type <code>Double</code> works. |
<syntaxhighlight lang="Haskell" class="myDark" > | <syntaxhighlight lang="Haskell" class="myDark" > | ||
Prelude> :type (5 + 8) :: Double | Prelude> :type (5 + 8) :: Double | ||
| Line 43: | Line 43: | ||
Implement following functions: | Implement following functions: | ||
| − | * Function that computes a factorial of given number. | + | * Function that computes a factorial of a given number. |
<syntaxhighlight lang="Haskell">factorial :: Int -> Int</syntaxhighlight> | <syntaxhighlight lang="Haskell">factorial :: Int -> Int</syntaxhighlight> | ||
| − | * Function that computes n-th number in | + | * Function that computes n-th number in Fibonacci sequence. |
<syntaxhighlight lang="Haskell">fib :: Int -> Int</syntaxhighlight> | <syntaxhighlight lang="Haskell">fib :: Int -> Int</syntaxhighlight> | ||
| − | * Function that checks if a year is a leap-year (divisible without remainder by 4 | + | * Function that checks if a year is a leap-year (divisible without remainder by 4 and it is not divisible by 100. If it is divisible by 400, it is a leap-year). |
<syntaxhighlight lang="Haskell">leapYear :: Int -> Bool</syntaxhighlight> | <syntaxhighlight lang="Haskell">leapYear :: Int -> Bool</syntaxhighlight> | ||
* Implement two functions that returns a maximum from 2 respectively 3 given parameters. | * Implement two functions that returns a maximum from 2 respectively 3 given parameters. | ||
| Line 54: | Line 54: | ||
max3 :: Int -> Int -> Int -> Int | max3 :: Int -> Int -> Int -> Int | ||
</syntaxhighlight> | </syntaxhighlight> | ||
| − | * Term combination is a selection of items from a collection, such that (unlike permutations) the order of selection does not matter. Compute the number of possible combinations if we are taking k things from the collection of n things. | + | * Term combination is a selection of items from a collection, such that (unlike permutations) the order of elements in this selection does not matter. Compute the number of possible combinations if we are taking k things from the collection of n things. |
<syntaxhighlight lang="Haskell">combinations :: Int -> Int -> Int</syntaxhighlight> | <syntaxhighlight lang="Haskell">combinations :: Int -> Int -> Int</syntaxhighlight> | ||
* Implement a function that computes the number of solutions for a quadratic equation. This quadratic equation will be given using standard coefficients: a, b, c. | * Implement a function that computes the number of solutions for a quadratic equation. This quadratic equation will be given using standard coefficients: a, b, c. | ||
| Line 64: | Line 64: | ||
* Implement a function that computes greatest common divider for two given numbers. | * Implement a function that computes greatest common divider for two given numbers. | ||
<syntaxhighlight lang="Haskell">gcd' :: Int -> Int -> Int</syntaxhighlight> | <syntaxhighlight lang="Haskell">gcd' :: Int -> Int -> Int</syntaxhighlight> | ||
| − | * Implement a function that compute, if a given number is a prime number | + | * Implement a function that compute, if a given number is a prime number. |
<syntaxhighlight lang="Haskell">isPrime :: Int -> Bool</syntaxhighlight> | <syntaxhighlight lang="Haskell">isPrime :: Int -> Bool</syntaxhighlight> | ||
Revision as of 08:08, 10 October 2019
Types
- Using the GHCi command
:info, learn the type of the following functions (and operators):+, sqrt, succ, max - Get the information about the data type of following expressions and evaluate them. it is possible using the command
:type. You can switch this option on for all commands by:set +t(removing by:unset +t).
5 + 8
3 * 5 + 8
2 + 4
sqrt 16
succ 6
succ 7
pred 9
pred 8
sin (pi / 2)
truncate pi
round 3.5
round 3.4
floor 3.7
ceiling 3.3
mod 10 3
odd 3
- At presentations, we have spoken about some basic types:
Int, Double, Bool, Char. For each of previous expressions assign them the most appropriate of these basic data types. You can verify your guess by using::. For example, for the first expression, let's assume it isInt. We can cast the result to integer and get the following result.
Prelude> :type (5 + 8) :: Int
(5 + 8) :: Int :: Int
If we try incorrect conversion to Char, we get the following result.
Prelude> :type (5 + 8) :: Char
<interactive>:1:2: error:
* No instance for (Num Char) arising from a use of `+'
* In the expression: (5 + 8) :: Char
For this expression, also the type Double works.
Prelude> :type (5 + 8) :: Double
(5 + 8) :: Double :: Double
Simple functions
Implement following functions:
- Function that computes a factorial of a given number.
factorial :: Int -> Int
- Function that computes n-th number in Fibonacci sequence.
fib :: Int -> Int
- Function that checks if a year is a leap-year (divisible without remainder by 4 and it is not divisible by 100. If it is divisible by 400, it is a leap-year).
leapYear :: Int -> Bool
- Implement two functions that returns a maximum from 2 respectively 3 given parameters.
max2 :: Int -> Int -> Int
max3 :: Int -> Int -> Int -> Int
- Term combination is a selection of items from a collection, such that (unlike permutations) the order of elements in this selection does not matter. Compute the number of possible combinations if we are taking k things from the collection of n things.
combinations :: Int -> Int -> Int
- Implement a function that computes the number of solutions for a quadratic equation. This quadratic equation will be given using standard coefficients: a, b, c.
numberOfRoots :: Int -> Int -> Int -> Int
-- To simplify the solution, let construct can be used
f x y = let a = x + y
in a * a
- Implement a function that computes greatest common divider for two given numbers.
gcd' :: Int -> Int -> Int
- Implement a function that compute, if a given number is a prime number.
isPrime :: Int -> Bool
