Preparations for exercise 5.
Merge branch 'exercise-4' into exercise-5
Merge branch 'exercise-4' into exercise-5
Merge branch 'exercise-4' into exercise-5
Merge branch 'exercise-4' into exercise-5
Merge branch 'master' into exercise-5
Merge branch 'master' into exercise-5
Move the difference.
Add accumulate-filter.
Add two more tasks.
Fix accumulate-filter.
Fixes.
Add 10derive-xy.
Add a let/let* example.
Housekeeping.
Formatting. Add a README.
Update README.md
Some clarifications.
Remove the extra tasks.
Merge branch 'exercise-5'