Guile’s built-in reader includes support for SRFI-105 curly-infix expressions. See the specification of SRFI-105. Some examples:
{n <= 5} ⇒ (<= n 5)
{a + b + c} ⇒ (+ a b c)
{a * {b + c}} ⇒ (* a (+ b c))
{(- a) / b} ⇒ (/ (- a) b)
{-(a) / b} ⇒ (/ (- a) b) as well
{(f a b) + (g h)} ⇒ (+ (f a b) (g h))
{f(a b) + g(h)} ⇒ (+ (f a b) (g h)) as well
{f[a b] + g(h)} ⇒ (+ ($bracket-apply$ f a b) (g h))
'{a + f(b) + x} ⇒ '(+ a (f b) x)
{length(x) >= 6} ⇒ (>= (length x) 6)
{n-1 + n-2} ⇒ (+ n-1 n-2)
{n * factorial{n - 1}} ⇒ (* n (factorial (- n 1)))
{{a > 0} and {b >= 1}} ⇒ (and (> a 0) (>= b 1))
{f{n - 1}(x)} ⇒ ((f (- n 1)) x)
{a . z} ⇒ ($nfx$ a . z)
{a + b - c} ⇒ ($nfx$ a + b - c)
To enable curly-infix expressions within a file, place the reader
directive #!curly-infix before the first use of curly-infix
notation. To globally enable curly-infix expressions in Guile’s reader,
set the curly-infix read option.
Guile also implements the following non-standard extension to SRFI-105:
if curly-infix is enabled and there is no other meaning assigned
to square brackets (i.e. the square-brackets read option is
turned off), then lists within square brackets are read as normal lists
but with the special symbol $bracket-list$ added to the front.
To enable this combination of read options within a file, use the reader
directive #!curly-infix-and-bracket-lists. For example:
[a b] ⇒ ($bracket-list$ a b) [a . b] ⇒ ($bracket-list$ a . b)
For more information on reader options, See Reading Scheme Code.