Tables below use k3-style f, x, y in adverb patterns. In the reference manual, primitive verbs use a and x for dyadic operands instead.
gk is not a byte-for-byte k3 clone. If you already know k3 (or a close derivative), this page collects the main surface-level differences so you can map habits to gk quickly.
For the full language from first principles, see the reference manual.
The verbs are all like k3. However, there is no "force monadic" (ex: #:'). The valence of primitive verbs (including composition) is always determined from context. A few examples:
#'(1 2;3 4 5)
2 3
!'2 3 4
(0 1
0 1 2
0 1 2 3)
*'("ab";"cd";"ef")
"ace"
(%-)'1 2 3
-1 -0.5 -0.3333333
The adverbs are similar to k3, but /: \: ': are gone. The only adverbs are / \ '. How they operate depends on the context and the valence of the modified verb. Here's a quick synopsis:
each f'x
each x f'y
each f'[x;y]
each f'[x;y;z]
scanm f\x
do n f\x
while b f\x
eachleft x f\y
eachleft f\[x;y]
scand f\x
scan f\[x;y;z]
overm f/x
do n f/x
while b f/x
eachright x f/y
eachright f/[x;y]
overd f/x
over f/[x;y;z]
eachprior ep[f;x]
slide is an enhanced version of eachprior from k3 (aka eachpair).
_[n;f;a]
The first argument is a positive or negative integer. Its sign indicates the order the arguments are passed to the modified verb. Its absolute value indicates the number of steps the sliding window moves each time arguments are taken. The second argument is a verb. The third argument is a vector or list. These examples should make clear how it works:
_[1;,;"abcd"]
("ab"
"bc"
"cd")
_[-1;,;"abcd"]
("ba"
"cb"
"dc")
_[2;,;"abcd"]
("ab"
"cd")
_[-2;,;"abcd"]
("ba"
"dc")
The case of _[-1;f;a] in gk is equivalent to f': a in k3. gk also has a builtin for eachprior.
ep[,]"asdf"
("sa"
"ds"
"fd")
Underscores are not allowed in variable names. It makes things cleaner since there is no longer a need to have space around the drop/cut verb.
a:1
b:1 2 3
a_b
2 3
Most of the reserved names from k3 are still there, but with the _ removed.
draw[10;10]
7 2 7 6 6 3 6 2 5 8
1 2 3 dv 2
1 3
2 vs 5
1 0 1
Some single-letter names have changed.
k3 gk
--- ----
_n nul
_P .z.P
_T .z.T
_f .z.f
_h .z.h
_i .z.i
_t .z.t
$[0;`a;`b]
`b
$[1;`a;`b]
`a
See also digraphs for each-left / each-right / each-prior notation.