.Dd September 24, 2026
.Dt TUMBLER-S7 7
.Os
.Sh NAME
.Nm tumbler-s7
.Nd S7 Scheme interface to the tumbler primitive
.Sh SYNOPSIS
Bd -literal -offset indent
(load "./build/lib/enfilade.so" (inlet 'init_func 'init_enfilade_s7))

(tumbler-compare "1" "1.1")
(tumbler-add "3" "2.16.3")
(tumbler-subtract "1.4.3" "1.1.1")
.Ed
.Sh DESCRIPTION
The module exposes the small C tumbler implementation to S7 without requiring
a separate Scheme tumbler object type.  Tumblers cross the FFI as dotted
unsigned-integer strings.
.Sh FUNCTIONS
.Bl -tag -width tumbler-subtract
.It Fn tumbler-compare a b
Returns a negative integer, zero, or a positive integer according to the
whole-tumbler ordering of
.Fa a
and
.Fa b .
.It Fn tumbler-add position offset
Returns a new tumbler string containing Xanadu tumbler addition.
.It Fn tumbler-subtract a b
Returns the generalized non-negative tumbler difference.
.El
.Sh EXAMPLES
.Bd -literal
(tumbler-compare "1" "1.1")
; => -1

(tumbler-add "3" "2.16.3")
; => "5.16.3"

(tumbler-add "25.6.46.93" "0.0.3.1.21")
; => "25.6.49.1.21"

(tumbler-subtract "1.4.3" "1.1.1")
; => "0.3.3"
.Ed
.Sh ERRORS
Malformed tumbler strings raise
.Ql TumblerAddressException .
Allocation failures raise
.Ql memory-error .
.Sh SEE ALSO
.Xr tumbler 3 ,
.Xr enfilade-s7 7
.Sh REFERENCES
.Lk https://sentido-labs.com/en/library/201904240732/Xanadu%20Hypertext%20Documents.html