samples/iyi/io.iyi

# IO: line-at-a-time reading of standard input.
#
#   printf "first line\nsecond line\nthird line\n" | ./bin/iyi run samples/iyi/io.iyi
#
# Reads standard input line by line through stdin.read_line, demonstrating
# buffered stream reading.

module samples/io

line_number = 0
while line = stdin.read_line(chomp: true)
  line_number = line_number + 1
  puts "#{line_number}: #{line}"
end

if line_number == 0
  puts "no lines read from standard input"
else
  puts "read #{line_number} line(s) from standard input"
end

Press Run.

recorded with iyi 0.18.0 (built on Crystal 1.22.0-dev [2a9653052] (2026-10-18)) · Linux 7.0.0-38-generic x86_64, QEMU Virtual CPU version 2.5+ · 2026-10-19

You can type in the pane: nothing here compiles, so what you type cannot run, and the page says which bytes it is running the moment the text stops being the recorded file. There is no standard input, no filesystem and no threads on this target, and one sample fails on purpose for exactly that reason.

Run executes iyi-io.wasm, the module the compiler built from this file, in your browser. How this works

$ iyi run io.iyi