SHOW SOLUTION via Bootstrap
This commit is contained in:
Michael Snoyman
parent
7c4b3b973d
commit
daad8d3bdc
1 changed files with 107 additions and 57 deletions
|
|
@ -477,7 +477,17 @@ main = do
|
|||
_ -> Prelude.putStrLn "Try again"
|
||||
```
|
||||
|
||||
@@@SHOW SOLUTION
|
||||
<div class="panel-group" id="accordion" role="tablist" aria-multiselectable="true">
|
||||
<div class="panel panel-default">
|
||||
<div class="panel-heading" role="tab">
|
||||
<h4 class="panel-title">
|
||||
<a role="button" data-toggle="collapse" data-parent="#accordion" href="#exerciseOne" aria-expanded="true" aria-controls="collapseOne">
|
||||
Show Solution
|
||||
</a>
|
||||
</h4>
|
||||
</div>
|
||||
<div id="exerciseOne" class="panel-collapse collapse" role="tabpanel">
|
||||
<div class="panel-body">
|
||||
|
||||
```haskell
|
||||
#!/usr/bin/env stack
|
||||
|
|
@ -491,7 +501,7 @@ main = do
|
|||
-- /show
|
||||
```
|
||||
|
||||
@@@
|
||||
</div></div>
|
||||
|
||||
2. How is `return` implemented for the `Maybe` monad? Try replacing `return`
|
||||
with its implementation in the code above.
|
||||
|
|
@ -508,7 +518,17 @@ main = do
|
|||
| otherwise = putStrLn "Incorrect, please try again"
|
||||
```
|
||||
|
||||
@@@SHOW SOLUTION
|
||||
<div class="panel-group" id="accordion" role="tablist" aria-multiselectable="true">
|
||||
<div class="panel panel-default">
|
||||
<div class="panel-heading" role="tab">
|
||||
<h4 class="panel-title">
|
||||
<a role="button" data-toggle="collapse" data-parent="#accordion" href="#exerciseTwo" aria-expanded="true" aria-controls="collapseTwo">
|
||||
Show Solution
|
||||
</a>
|
||||
</h4>
|
||||
</div>
|
||||
<div id="exerciseTwo" class="panel-collapse collapse" role="tabpanel">
|
||||
<div class="panel-body">
|
||||
|
||||
`return` is simply the `Just` constructor. This gets defined as:
|
||||
|
||||
|
|
@ -517,7 +537,7 @@ main = do
|
|||
return = Just
|
||||
```
|
||||
|
||||
@@@
|
||||
</div></div>
|
||||
|
||||
3. `yearDiff` is really just subtraction. Try to replace the calls to
|
||||
`yearDiff` with explicit usage of the `-` operator.
|
||||
|
|
@ -549,7 +569,17 @@ main = do
|
|||
displayAge maybeAge
|
||||
```
|
||||
|
||||
@@@SHOW SOLUTION
|
||||
<div class="panel-group" id="accordion" role="tablist" aria-multiselectable="true">
|
||||
<div class="panel panel-default">
|
||||
<div class="panel-heading" role="tab">
|
||||
<h4 class="panel-title">
|
||||
<a role="button" data-toggle="collapse" data-parent="#accordion" href="#exerciseThree" aria-expanded="true" aria-controls="collapseThree">
|
||||
Show Solution
|
||||
</a>
|
||||
</h4>
|
||||
</div>
|
||||
<div id="exerciseThree" class="panel-collapse collapse" role="tabpanel">
|
||||
<div class="panel-body">
|
||||
|
||||
```haskell
|
||||
#!/usr/bin/env stack
|
||||
|
|
@ -578,7 +608,7 @@ main = do
|
|||
displayAge maybeAge
|
||||
```
|
||||
|
||||
@@@
|
||||
</div></div>
|
||||
|
||||
4. It's possible to write an applicative functor version of the
|
||||
auto-reverse-arguments code by modifying the `yearDiff` function. Try to do
|
||||
|
|
@ -604,7 +634,17 @@ main = do
|
|||
| otherwise = putStrLn "Please try again"
|
||||
```
|
||||
|
||||
@@@ SHOW SOLUTION
|
||||
<div class="panel-group" id="accordion" role="tablist" aria-multiselectable="true">
|
||||
<div class="panel panel-default">
|
||||
<div class="panel-heading" role="tab">
|
||||
<h4 class="panel-title">
|
||||
<a role="button" data-toggle="collapse" data-parent="#accordion" href="#exerciseFour" aria-expanded="true" aria-controls="collapseFour">
|
||||
Show Solution
|
||||
</a>
|
||||
</h4>
|
||||
</div>
|
||||
<div id="exerciseFour" class="panel-collapse collapse" role="tabpanel">
|
||||
<div class="panel-body">
|
||||
|
||||
```haskell
|
||||
#!/usr/bin/env stack
|
||||
|
|
@ -637,65 +677,75 @@ main = do
|
|||
displayAge maybeAge
|
||||
```
|
||||
|
||||
@@@
|
||||
</div></div>
|
||||
|
||||
* Now try to do it without modifying `yearDiff` directly, but by using a
|
||||
helper function which is applied to `yearDiff`.
|
||||
5. Now try to do it without modifying `yearDiff` directly, but by
|
||||
using a helper function which is applied to `yearDiff`.
|
||||
|
||||
```haskell
|
||||
#!/usr/bin/env stack
|
||||
-- stack --resolver lts-7.14 runghc
|
||||
import Text.Read (readMaybe)
|
||||
import Control.Applicative ((<$>), (<*>))
|
||||
```haskell
|
||||
#!/usr/bin/env stack
|
||||
-- stack --resolver lts-7.14 runghc
|
||||
import Text.Read (readMaybe)
|
||||
import Control.Applicative ((<$>), (<*>))
|
||||
|
||||
displayAge maybeAge =
|
||||
case maybeAge of
|
||||
Nothing -> putStrLn "You provided invalid input"
|
||||
Just age -> putStrLn $ "In that year, you will be: " ++ show age
|
||||
displayAge maybeAge =
|
||||
case maybeAge of
|
||||
Nothing -> putStrLn "You provided invalid input"
|
||||
Just age -> putStrLn $ "In that year, you will be: " ++ show age
|
||||
|
||||
yearDiff futureYear birthYear = futureYear - birthYear
|
||||
-- show
|
||||
yourHelperFunction f ...
|
||||
-- /show
|
||||
yearDiff futureYear birthYear = futureYear - birthYear
|
||||
-- show
|
||||
yourHelperFunction f ...
|
||||
-- /show
|
||||
|
||||
main
|
||||
| yourHelperFunction yearDiff 5 6 == 1 = putStrLn "Correct!"
|
||||
| otherwise = putStrLn "Please try again"
|
||||
```
|
||||
main
|
||||
| yourHelperFunction yearDiff 5 6 == 1 = putStrLn "Correct!"
|
||||
| otherwise = putStrLn "Please try again"
|
||||
```
|
||||
|
||||
@@@ SHOW SOLUTION
|
||||
<div class="panel-group" id="accordion" role="tablist" aria-multiselectable="true">
|
||||
<div class="panel panel-default">
|
||||
<div class="panel-heading" role="tab">
|
||||
<h4 class="panel-title">
|
||||
<a role="button" data-toggle="collapse" data-parent="#accordion" href="#exerciseFive" aria-expanded="true" aria-controls="collapseFive">
|
||||
Show Solution
|
||||
</a>
|
||||
</h4>
|
||||
</div>
|
||||
<div id="exerciseFive" class="panel-collapse collapse" role="tabpanel">
|
||||
<div class="panel-body">
|
||||
|
||||
```haskell
|
||||
#!/usr/bin/env stack
|
||||
-- stack --resolver lts-7.14 runghc
|
||||
import Text.Read (readMaybe)
|
||||
```haskell
|
||||
#!/usr/bin/env stack
|
||||
-- stack --resolver lts-7.14 runghc
|
||||
import Text.Read (readMaybe)
|
||||
|
||||
displayAge maybeAge =
|
||||
case maybeAge of
|
||||
Nothing -> putStrLn "You provided invalid input"
|
||||
Just age -> putStrLn $ "In that year, you will be: " ++ show age
|
||||
displayAge maybeAge =
|
||||
case maybeAge of
|
||||
Nothing -> putStrLn "You provided invalid input"
|
||||
Just age -> putStrLn $ "In that year, you will be: " ++ show age
|
||||
|
||||
yearDiff futureYear birthYear = futureYear - birthYear
|
||||
yearDiff futureYear birthYear = futureYear - birthYear
|
||||
|
||||
main = do
|
||||
putStrLn "Please enter your birth year"
|
||||
birthYearString <- getLine
|
||||
putStrLn "Please enter some year in the future"
|
||||
futureYearString <- getLine
|
||||
let maybeAge = do
|
||||
futureYear <- readMaybe futureYearString
|
||||
birthYear <- readMaybe birthYearString
|
||||
return $
|
||||
if futureYear < birthYear
|
||||
then yourHelperFunction yearDiff birthYear futureYear
|
||||
else yourHelperFunction yearDiff futureYear birthYear
|
||||
displayAge maybeAge
|
||||
main = do
|
||||
putStrLn "Please enter your birth year"
|
||||
birthYearString <- getLine
|
||||
putStrLn "Please enter some year in the future"
|
||||
futureYearString <- getLine
|
||||
let maybeAge = do
|
||||
futureYear <- readMaybe futureYearString
|
||||
birthYear <- readMaybe birthYearString
|
||||
return $
|
||||
if futureYear < birthYear
|
||||
then yourHelperFunction yearDiff birthYear futureYear
|
||||
else yourHelperFunction yearDiff futureYear birthYear
|
||||
displayAge maybeAge
|
||||
|
||||
-- show
|
||||
yourHelperFunction f x y
|
||||
| x > y = f x y
|
||||
| otherwise = f y x
|
||||
-- /show
|
||||
```
|
||||
-- show
|
||||
yourHelperFunction f x y
|
||||
| x > y = f x y
|
||||
| otherwise = f y x
|
||||
-- /show
|
||||
```
|
||||
|
||||
@@@
|
||||
</div></div>
|
||||
|
|
|
|||
Loading…
Reference in a new issue