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Here's a WIP implementation of theK 2.0 language in OCaml (4.02.3). Some basic things already work. A whole bunch of things does not (yet).

fun, practice etc

Kona wiki,K 2.0 reference andmanual.

TheIslands example from the Kona wiki (Given a binary matrix, identifies "islands" of 1's and sequentially numbers them):

  grid:(1 0 0 0 1        1 1 1 0 0        0 0 0 0 1        0 0 0 1 1        1 0 1 1 1        0 0 1 0 1)  col:  {x*(^x)#1+!*/^x}                   / give each 1 a unique id  ab:   {e:{(0,)'x};+(e(+e x))}            / add a border of zeroes  rb:   {(1_)'1_ x}                        / remove the border of zeroes  adj:  {(,x),(-1 1!'\:x),(-1 1)!\:x}      / adjacent cells  mrg:  {(~~x)*|/adj x}                    / merge neighboring ids  rc:   {.[x;(;);(?0,,/x)?]}               / renumber ids sequentially  isl:  {rc rb(mrg/col ab x)}              / find islands  isl grid(1 0 0 0 2 1 1 1 0 0 0 0 0 0 3 0 0 0 3 3 4 0 3 3 3 0 0 3 0 3)

Short examples fromNinety-Nine K problems andK idioms:

  compress:{x@&1,~=':x}  compress "aaaaabbbccdddeee""abcde"  ? "aaaaabbbccdddeee"  /same result using the range operator"abcde"  powerset:{x@&:'!2+&#x}  powerset (`a;1;"test")(() ,"test" ,1 (1;"test") ,`a (`a;"test") (`a;1) (`a;1;"test"))

Loading a CSV file as a column dictionary:

$ cat test.csvsymbols,strings,integers,floats"abc","def 123",4,5.6"ghi","ijk 456",7,89.10$ ./k.native  table:.{(x;y)}'.("SCIF";,",") 0: "test.csv".((`symbols   `abc `ghi   )  (`strings   ("def 123";"ijk 456")   )  (`integers   4 7   )  (`floats   5.6 89.1   ))

• Make sure you haveOCaml (>=4.02.3) installed. If you are using theopam package manager (recommended), you can check this usingopam switch and, if you are using an older version, switch to 4.02.3 usingopam switch 4.02.3.
• Build the executable:make k
• (Optionally) run the end-to-end tests:make test-e2e

Messy, but getting there.ok currently implements just enough to "play around with K". Many features essential to a production system are missing.

The core language is covered almost entirely, while the standard library is quite incomplete.

• Entirely missing: FFI, IPC, networking, date/time ops, attributes, UI.

• Functions can be serialized, but neither their source nor their AST is preserved.

• K-tree namespaces are not faithfully implemented yet. In particular, assignments to the current directory do not have the desired effect (a separate copy is created on writes).As a special-case workaround, the current workspace (entire K-tree) can be saved/loaded to/from disk using the (non-standard) "\load" and "\save" commands:

    $ ./k.native  ┌──────────┐  │ok console│  └──────────┘    test:123    \save "my_workspace"  "my_workspace"    \\  $ ./k.native  ┌──────────┐  │ok console│  └──────────┘    \load "my_workspace"  "my_workspace"    test  123

• Performance is currently terrible. In particular,Amend always creates a deep copy, even if the structure is only being referenced once.

• Compiler warnings: many partial patterns. Mainly due to infeasible cases omitted for brevity.