S-Expressions in Lua

Manipulating S-Expressions

See cells.lua

local cells = require 'cells'

local cons = cells.cons
local car  = cells.car
local cadr = cells.cadr
local cddr = cells.cddr
local list = cells.list
-- etc.

local _, c = list(3, 'A', 'B', 'C')
print(c)       -- (A B C)
print(car(c))  -- A
print(cadr(c)) -- B
print(cddr(c)) -- (C)

Reading S-Expresions

local reader = require 'reader'

local r = reader.new('(A    (B    "string"    -123.456    (C . D))) (x y)')
local c, errors = r:read()

print(#c)   -- 2
print(c[1]) -- (A (B "string" -123.456 (C . D))
print(c[2]) -- (x y)

See reader.lua

More examples

See test.lua for examples on how to do reading and for examples of use of 'map', 'zip' and 'apply'.

Features

• 2014-01-23: list, map, apply, zip. Since Lua does not handle varargs properly adding an integer as companion to all varargs '{...}' and as result to all 'return' clauses.

• 2014-01-21: reads quoted strings, parses some Scheme source code

• 2014-01-20: cons, cdr, car, set-car, set-cdr et al cells.lua.

• 2014-01-20: prints cells with cycles

• 2014-01-20: a reader with line/column debugging info reader.lua

• 2014-01-20: The in_c directory keeps an old C version that does not handle cycles properly (GC), but it's still kept there for historical reasons.