CSV

Parse and generate CSV (Comma-Separated Values) data. Supports custom delimiters, header rows, and proper escaping of special characters.

import Encoding.CSV

Parsing

CSV.parse

String -> [[String]]

Parse a CSV string into a list of rows, where each row is a list of fields.

csv = "name,age,city\nAlice,30,NYC\nBob,25,LA"
rows = CSV.parse csv
# [["name", "age", "city"], ["Alice", "30", "NYC"], ["Bob", "25", "LA"]]

CSV.parse-headers

String -> [a]

Parse CSV with the first row as headers. Returns a list of records where each record has fields named after the headers.

csv = "name,age\nAlice,30\nBob,25"
records = CSV.parse-headers csv
# [{name: "Alice", age: "30"}, {name: "Bob", age: "25"}]

CSV.parse-row

String -> [String]

Parse a single CSV row into a list of fields.

row = CSV.parse-row "Alice,30,NYC"
# ["Alice", "30", "NYC"]

Custom Delimiters

All parsing functions have -with variants that accept a custom delimiter. Useful for TSV (tab-separated), pipe-separated, or other formats.

CSV.parse-with

String -> String -> [[String]]

Parse with a custom delimiter character.

# Parse tab-separated values
tsv = "name\tage\nAlice\t30"
rows = CSV.parse-with "\t" tsv

# Parse pipe-separated values
psv = "name|age\nAlice|30"
rows = CSV.parse-with "|" psv

CSV.parse-headers-with

String -> String -> [a]

Parse with headers using a custom delimiter.

CSV.parse-row-with

String -> String -> [String]

Parse a single row with a custom delimiter.

Formatting

CSV.to-csv

[[String]] -> String

Format rows into a CSV string.

rows = [["name", "age"], ["Alice", "30"]]
csv = CSV.to-csv rows
# "name,age\nAlice,30"

CSV.to-csv-with

String -> [[String]] -> String

Format rows with a custom delimiter.

CSV.row-to-csv

[String] -> String

Format a single row into a CSV line.

CSV.row-to-csv-with

String -> [String] -> String

Format a single row with a custom delimiter.

CSV.escape

String -> String

Escape a field for CSV output. Adds quotes if the field contains commas, quotes, or newlines.

escaped = CSV.escape "Hello, World"
# "\"Hello, World\""

File I/O

File Capabilities Required

File-backed CSV helpers require file authority in scope. Reads require FileReadAuth, FileAuth, or RootAuth; writes require FileWriteAuth, FileAuth, or RootAuth. Pure parsing helpers such as CSV.parse and CSV.generate do not require file authority.

CSV.read

String -> Result [[String]] IOError

Read and parse a CSV file. Requires FileReadAuth, FileAuth, or RootAuth in scope.

import Auth.File.{file-auth, file-read-auth}

main = fn(env: Env) =>
  read-auth = file-read-auth (file-auth env.root)
  match CSV.read "data.csv"
    | Ok rows -> process rows
    | Err e -> println "Error reading file: ${e}"

CSV.read-with

String -> String -> Result [[String]] IOError

Read a file with a custom delimiter. Requires read file authority in scope.

CSV.read-headers

String -> Result [a] IOError

Read a CSV file with the first row as headers. Requires read file authority in scope.

CSV.read-headers-with

String -> String -> Result [a] IOError

Read a file with headers and a custom delimiter. Requires read file authority in scope.

CSV.auto-read

FileReadAuth -> String -> Result [[String]] IOError

Read a CSV file, detect its delimiter, and parse rows.

match CSV.auto-read read-auth "data.csv"
  | Ok rows -> process rows
  | Err e -> println "Error: ${e}"

CSV.auto-read-headers

FileReadAuth -> String -> Result [a] IOError

Read a CSV file, detect its delimiter, and parse the first row as headers.

CSV.write

String -> [[String]] -> Result () IOError

Write rows to a CSV file. Requires FileWriteAuth, FileAuth, or RootAuth in scope.

import Auth.File.{file-auth, file-write-auth}

main = fn(env: Env) =>
  rows = [["name", "age"], ["Alice", "30"]]
  write-auth = file-write-auth (file-auth env.root)

  match CSV.write "output.csv" rows
    | Ok _ -> println "Saved successfully"
    | Err e -> println "Error: ${e}"

CSV.write-with

String -> String -> [[String]] -> Result () IOError

Write to a file with a custom delimiter. Requires write file authority in scope.