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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 homoiconic1, generic2, and backwards-compatible3. 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 (clone).

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.

Requirements

Setup

From the repository:

  • Get wisp: hg clone http://draketo.de/proj/wisp (needs Mercurial)
  • Bootstrap: cd wisp && autoreconf -i && ./configure && make

From a release:

Install

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_COMPILED_PATH=${HOME}/.local/lib/guile/2.2/site-ccache{GUILE_LOAD_COMPILED_PATH:+:}${GUILE_LOAD_COMPILED_PATH}
export GUILE_LOAD_PATH=${HOME}/.local/share/guile/site/2.2/${GUILE_LOAD_PATH:+:}${GUILE_LOAD_PATH}

More

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

Usage

  • 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

Notes

Standardization: Wisp is standardized as SRFI 11945.

Copyright: 2013--2015 Arne Babenhauserheide

License: GPLv3 or later

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Footnotes

  1. Wisp is homoiconic because everything you write gets turned into lisp which is homoiconic. ↩

  2. 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. ↩

  3. Wisp is backwards compatible, because you can use arbitrary lisp code in wisp: Indentation processing skips expressions in brackets. ↩

  4. 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/. ↩

  5. 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. ↩