» I love the syntax of Python, but crave the simplicity and power of Lisp.«
merge stable into default after release
Added signature for changeset 3015b7813947
Added tag v1.0.12 for changeset 7c6239a77965
wisp 1.0.12: improve compatibility and output
update NEWS and version to 1.0.12
fix: do not include doctest output in examples


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#Wisp: Whitespace to Lisp

define : hello                    (define (hello)
  display "Hello World"     ⇒        (display "Hello World"))

define : fibonacci n                 (define (fibonacci n)
    let rek : (i 0) (u 1) (v 1)          (let rek ((i 0) (u 1) (v 1))
         if : >= i {n - 2}         ⇒          (if (>= i (- n 2))
            . v                                    v
            rek {i + 1} v {u + v}                 (rek (+ i 1) v (+ u v)))))

Wisp turns indentation based syntax into Lisp. The conversion is homoiconic[^h], generic[^g], and backwards-compatible[^b]. It is inspired by project readable, but tries to keep itself simple (and stupid: just add parens for indentation).

More information is available on the wisp-website, and code in the wisp-repository

For a short presentation, see Why Wisp?

Note that this is full-fledged scheme, with all its capabilities like hygienic macros (programmable syntax!) and full tail recursion.



From the repository:

  • Get wisp: hg clone http://hg.sr.ht/~arnebab/wisp (needs Mercurial)
  • Bootstrap: cd wisp && autoreconf -i && ./configure && make

From a release:

  • Get a release from the wisp-website: draketo.de/english/wisp
  • Unpack and build: tar xf [release].tar.gz; cd [release]; ./configure; make


Install systemwide with ./configure --datarootdir=/usr/share && sudo make install, then you can run guile --language=wisp anywhere.

Install in your home folder with ./configure --datarootdir=$HOME/.local; make install. Use guile -c '(import (language wisp spec))' to get rid of auto-compile errors. You might need to set the module paths in ~/.bash_profile:

export GUILE_LOAD_PATH=${HOME}/.local/share/guile/site/2.2/${GUILE_LOAD_PATH:+:}${GUILE_LOAD_PATH}


Run tests with make check. Distribute your own version with make distcheck.

If your Guile is installed in your home, you might need to use ./configure PKG_CONFIG_PATH=$HOME/.local/lib/pkgconfig/ and make distcheck PKG_CONFIG_PATH=$HOME/.local/lib/pkgconfig/

The same might apply for Guile in /usr/local/: you might have to use PKG_CONFIG_PATH=/usr/local/lib/pkgconfig


  • Preprocess files: ./wisp2lisp infile.wisp > outfile.scm
  • Wisp at the REPL: guile -L . --language=wisp # in the wisp-folder
  • The files in examples/ show how to make executable wisp programs.

#Wisp and curly infix (SRFI-105)

Wisp treats braces "{}" the same as parentheses "()" and square brackets "[]", so you can use it with curly infix (SRFI-105) to get more customary math expressions. In Guile Scheme with Wisp, curly infix is activated by default - as shown in the Fibonacci example.

If you want to use a curly-infix expression starting a line, you have to prefix it with a dot:

. {1 + 1}
; = 2


Wisp as project is licensed under the GPLv3 or later. See COPYING for details. This explicitly includes the files examples/* and emacs lisp files.

The implementation of wisp as language and implementation of SRFI-119 as well as the tests and supporting files are licensed under the lax expat-license: wisp-guile.w, wisp-scheme.w, wisp-reader.w, Makefile.am, configure.ac, bootstrap.sh, bootstrap-reader.sh, systaxtestsreader.sh, syntaxtests.sh, tests/*, testrunner.w, README.md, and other files required to use wisp as the language.

Providing wisp the language under the expat-license to make it easier to embed wisp in games that use Guile.


Standardization: Wisp is standardized as SRFI 119[^srfi][^ess].

[^srfi]: SRFI is the abbreviation of Scheme Request for Implementation. It is the official schemisch way of suggesting new features. SRFIs are maintained at srfi.schemers.org/.

[^ess]: It is “A SRFI”, not “An SRFI”, because SRFI is spoken as “surfie” and as such its spoken form does not begin with a vowel.

Copyright: 2013--2021 Arne Babenhauserheide

License: GPLv3 or later, except where noted differently in the source files. wisp-scheme.w, wisp-guile.w and wisp-reader.w are licensed under the expat license. Wisp as complete project is under the GPLv3 or later.

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[^h]: Wisp is homoiconic because everything you write gets turned into lisp which is homoiconic.

[^g]: Wisp is generic, because it works for any language which uses brackets to start a function call - which is true for most lisps. You simply get rid of the speerwall of parentheses without losing their power.

[^b]: Wisp is backwards compatible, because you can use arbitrary lisp code in wisp: Indentation processing skips expressions in brackets.