Data & I/O

ilo has built-in support for reading and writing files, making HTTP requests, and accessing environment variables. All I/O builtins return R (Result) types - use ! to auto-unwrap.

Reading files

rd path reads a file with format auto-detected from the extension:

Extension	Returns
`.csv`	`R _ t` — list of lists (grid)
`.tsv`	`R _ t` — list of lists (grid)
`.json`	`R _ t` — parsed JSON value
other	`R _ t` — raw text string

load p:t>R _ t;rd p

Force a specific format with a second argument:

load p:t>R _ t;rd p "json"

Reading lines

rdl path reads a file as a list of lines:

lines p:t>R L t t;rdl p

Parsing buffers

rdb string format parses a string in a given format - useful for data received from HTTP responses:

parse s:t>R _ t;rdb s "json"

Writing files

wr path data writes data to a file. Format can be specified as a third argument:

save>R t t;wr "out.txt" "hello world"

Structured output with format:

csv>R t t;wr "out.csv" [[1,2],[3,4]] "csv"
json>R t t;wr "data.json" [1,2,3] "json"

HTTP requests

get url makes an HTTP GET request. $url is a terse alias:

fetch url:t>R t t;$url

Auto-unwrap with ! to skip Result handling:

fetch url:t>t;$!url

post url body makes an HTTP POST:

send url:t body:t>R t t;post url body

Custom headers

Build a header map with mmap/mset and pass it as the last argument:

fetch url:t key:t>R t t
  h=mmap
  h=mset h "Authorization" key
  get url h

POST with custom headers works the same way:

send url:t body:t key:t>R t t
  h=mmap
  h=mset h "x-api-key" key
  post url body h

HTTP builtins (get, $, post) require the native binary. The npm/WASM build does not support network access.

Environment variables

env key reads an environment variable, returning R t t:

home>R t t;env "HOME"

Auto-unwrap with !:

home>t;env! "HOME"

.env and .env.local files in the working directory are loaded automatically.