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fn and over

Tired of writing the same basic, boring lambda bindings over and over again.

Let’s automate that.

(fn (cons x rest))

is shorthand for (lambda (x . rest) (cons x rest))

and

(fn (print y) (+ x z))

is shorthand for (lambda (x y z) (print y) (+ x z)).

fn

(fn body ...)

is shorthand for

(lambda some-basic-bindings body ...)

where some-basic-bindings is one of

args
(x . rest)
(x y . rest)
(x y z . rest)

and the fn macro automatically figures out which of those four you mean. Note that the length of rest will be different based on the presence of y or z.

over

(over body ...)

is shorthand for

(cut map (lambda some-basic-bindings body ...) <>)

except that the map can take any number of lists and that i is also anaphorically bound to the list index in body.

Here is an example:

((over (+ x x y i))
 '(10 20 40) '(3 6 9))

⇒ (23 47 91)

Implementation

fn and over are part of the brev-separate egg for chicken. For source code,

git clone https://idiomdrottning.org/brev-separate

Thanks to Chris Brannon and Juergen Lorenz for the idea.