Adapted from Al Sweigart's The Big Book of Small Python Projects: 81 Easy Practice Programs (No Starch Press, 2021; copyright © 2021 Al Sweigart), which he makes freely available under a Creative Commons Attribution-NonCommercial-ShareAlike licence at inventwithpython.com/bigbookpython. Changes were made: each program was ported from Python to EK9 and remodelled in EK9's idioms.

Project 35 — Hex Grid

This is project 35 of the book, ported to EK9. Its chapter is still being written; until then, this page shows the port itself: a run of it, the whole program, and how it keeps to the original.

A sample run

Run it with:

ek9 hex-grid.ek9

It prints:

/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_
\_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ 
/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_
\_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ 
/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_
\_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ 
/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_
\_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ 
/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_
\_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ 
/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_
\_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ 
/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_
\_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ 
/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_
\_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ 
/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_
\_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ 
/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_
\_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ 
/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_
\_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ 
/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_
\_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/ \_/

The program

#!ek9
defines module bigbook.hexgrid

  defines constant

    //The book's X_REPEAT and Y_REPEAT: hexagons across, and pairs of lines down.
    XRepeat <- 19
    YRepeat <- 12

    //One hexagon's share of each line of a row: the marks the grid is drawn with.
    TopTile <- "/ \\_"
    BottomTile <- "\\_/ "

  defines class

    //THE OUTPUT: everything the reader sees goes through here. The grid has no words, so there
    //is no Say, and it reads no input, so there is no LineInput.
    Console
      stdout as Stdout: Stdout()

      //The grid is computed: it is shown as the game drew it.
      showGrid()
        -> grid as List of String
        for line in grid
          stdout.println(line)

      override operator ? as pure
        <- rtn as Boolean: true

  defines function

    //THE GAME: the grid, as lines, with no output.

    //A pure function may not change a variable once it is set (E08120), so there is no
    //accumulator here: n copies are one copy followed by n - 1 copies.
    repeated() as pure
      ->
        text as String
        times as Integer
      <- rtn as String: times > 0 <- text + repeated(text, times - 1) : ""

    //The two lines of a row of hexagons are built once, then the rows are stacked.
    gridLines()
      <- rtn as List of String: List() of String
      top <- repeated(TopTile, XRepeat)
      bottom <- repeated(BottomTile, XRepeat)
      for rowPair in 1 ... YRepeat
        rtn += top
        rtn += bottom

  defines program

    //Hex Grid (Big Book project 35). Tessellates a grid of hexagons. The game decides; the
    //Console shows it.
    HexGrid()
      console <- Console()

      console.showGrid(gridLines())

About this port

Faithful to the book: a fixed grid, XRepeat (19) hexagons across and YRepeat (12) pairs of lines down, 24 lines in all, taking no input. (An earlier port took a width argument and printed three pairs; reconciliation fixed it.)
Idioms: String has no repeat operator, so repeated builds one. It is as pure, and a pure function cannot add to an accumulator (E08120), so it is written as recursion: n copies are one copy followed by n - 1. The two lines are built once and stacked YRepeat times by a range loop.