SRFI 2 - `and-let*`

The (srfi 2) library provides the and-let* macro, an and with local bindings.

Like an ordinary and, an and-let* special form evaluates its arguments -- expressions -- one after another in order, till the first one that yields #f. Unlike and, however, a non-#f result of one expression can be bound to a fresh variable and used in the subsequent expressions. and-let* is a cross-breed between let* and and.

See the SRFI document for more information.

and-let*

#and-let* (and-let* (claws) body

claws ::= '() | (cons claw claws)
claw  ::=  (variable expression) | (expression) |
           bound-variable

The claws are evaluated in the strict left-to-right order
For each claw, the expression part is evaluated first (or bound-variable is looked up)
If the result is #f, and-let* immediately returns #f
Otherwise, if the claw is of the form (variable expression) the expression's value is bound to a freshly made variable
The variable is available for the rest of the claws , and the body
As usual, all variables must be unique (like in let*)

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SRFI 2 - and-let*

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Raw Blame History

SRFI 2 - `and-let*`