6.8.7.8 Fluid bindings for loop syntaxes

Fluid Syntax: continue

Causes the innermost do, while, until or for loop to jump immediately to the next iteration. Being a fluid syntax: it is possible to use this keyword in custom syntaxes.

Fluid Syntax: break

Causes the innermost do, while, until or for loop to exit immediately to the continuation of the whole loop syntax. Being a fluid syntax: it is possible to use this keyword in custom syntaxes.

Vicare does not bind break and continue in uses of the named let syntax; this is because:

• Named let is a convenience syntax to define a recursive function; recursive functions do not have the break and continue operators in other languages. In Scheme, all the loop syntaxes are just convenience for a recursive function definition, but the named let is more so.
• The operation performed by continue in a named let is just performed by calling the function itself. Calling the function is more flexible because it allows tail calls and non–tail calls.
• The operation performed by break in a recursive function can be performed using returnable and return in the body:

  (returnable
    (let loop ()
      ...
      (return)
      ...))
  

• By keeping named let clean of fluid bindings, we can more freely use it as building block for custom loop syntaxes.