What's the difference between set-macro-character and set-dispatch-macro-character?

Question

From the signatures of these functions, the obvious difference is that set-macro-character allows you to set reader macro function for a single character, and set-dispatch-macro-character allows you to set it for any combination of two characters. Is this the only difference? When do I need to use one instead of another?

Answer 1

set-macro-character governs reading objects marked with a single special character, e.g.,

• lists (...)
• comments ; ...

set-dispatch-macro-character governs reading objects marked with two (or more) characters, e.g.,

• vectors #(...)
• arrays #A(...)
• structures #S(...)

See

• 2.1.4.4 Macro Characters
• 2.4 Standard Macro Characters
• 2.4.8 Sharpsign