Course of Raku / Advanced / Control flow

Statement prefixes 🆕

A statement prefix is a keyword placed in front of a statement or block to change how it is run. You have already met one — gather, which collects everything a block hands to take. This section introduces a few more general-purpose prefixes.

With prefixes you can turn a block into an expression that yields a value (do), control whether a list is computed immediately or on demand (eager and lazy), and run code purely for its side effects or with its warnings silenced (sink and quietly).

Topics in this section

• do and the value of a block
• Laziness and eagerness
• sink and quietly

Practice

Complete the quizzes that cover the contents of this section.

• Quiz — do
• Quiz — Statement prefixes

Exercises

This section contains 3 exercises. Examine all the topics of this section before doing the coding practice.

1. The value of a do block
2. Force eager evaluation
3. Silence a warning

Course navigation

← Quiz — gather   |   do and the value of a block →