Working with Libraries¶

Importing Standard Libraries¶

Every R7RS program starts by importing what it needs:

(import (scheme base))
(import (scheme write))
(display (+ 1 2))
(newline)

Multiple imports can be combined:

(import (scheme base)
        (scheme write)
        (scheme char))

Import Modifiers¶

;; Import only specific names
(import (only (scheme base) map filter))

;; Import everything except certain names
(import (except (scheme base) error))

;; Rename on import
(import (rename (scheme base) (map scheme-map)))

;; Add a prefix to all imported names
(import (prefix (scheme char) char:))
(char:char-alphabetic? #\A)  ;=> #t

Available Libraries¶

Kaappi includes all 14 R7RS standard libraries, 9 built-in SRFIs, and 42 portable SRFIs. See the Library Reference for the complete list.

Writing Your Own Library¶

Create a file mylib/math.sld:

(define-library (mylib math)
  (export square cube factorial)
  (import (scheme base))
  (begin
    (define (square x) (* x x))
    (define (cube x) (* x x x))
    (define (factorial n)
      (let loop ((i n) (acc 1))
        (if (= i 0) acc
            (loop (- i 1) (* i acc)))))))

Use it from another file:

(import (mylib math))
(display (factorial 10))  ;=> 3628800
(newline)

Library Search Paths¶

Kaappi searches for .sld files in this order:

The current directory (./)
The ./lib/ subdirectory
Directories specified with --lib-path

The library name (mylib math) maps to the file path mylib/math.sld.

kaappi --lib-path /path/to/libs program.scm

See the Library Reference for export specs, import modifiers, bytecode caching, cond-expand, and the complete library list.

Next: Advanced Features