foo.md

You may have noticed that our two functions above used different blocks; the first being when and the second if. You will often see one or the other used as a conditional, but it's not always immediately apparent why. In general, the reasons to use when are:

• There is no else-part associated with the result of a conditional
• You require an implicit do in order to perform side-effects

The reasons for the use of if would therefor be the inverse of those above.