AirScript

A scripting language for spreadsheet formulas, CLI tools, ETL pipelines.

Aka can be used as transformers:

• cells → script → cell
• stdin | script | stdout
• read query → script → write query

Ideas

• No side-effects (external data is stored in vars on start)
• Pure (and probably lazy)
• No modules/packages (but extensive stdlib)
• Hard resource constraints (runtime, memory, cycles)
• Typed (but no type annotations, only inference)
• No recursive functions (prevents endless loops)
• No currying
• JIT compiled (No overhead of managing both the source and the binary)
• List of available files (file content) in frontmatter
  • With support for globbing

Observations

Input data is untyped.

• It's a lot of effort to generate all the necessary types to represent the data. (As seen in Elm and Haskell.)
• TypeScript shows how runtime type-checking can be very helpful here.

Syntax

• Everything that starts with $ (constants, variables, …) or starts with a capital letter (types, namespaces, …) is provided by the prelude (aka standard library)
• Syntax sugar for f(g(h(i(j()))))
  • Maybe f@g@h@i@j()
• when … is …
  • Syntax sugar for boolean:

    when x is
    true "Good job!"
    false "Try again!"

• TODO: Maybe use Yes/No instead of True/False YesNo = Yes | No

Types

• Number
  • 0, 2, …
  • 3.14, …
  • TODO: Maybe Rational would be a better default
• Text
  • "With spaces"
  • 'single (Also called atoms)
• Result (Result ok = Ok(ok) | Error(Text))
  • No support for custom Error types, as one can use atoms and map them to full error messsages at the end
• Options (e.g. Options['north, 'east, 'south, 'west])

Examples

Manipulating JSON:

---
description: Convert item prices from € to % of total price
tags: [json]
---

json_result = $parse_json($input)

items_result = when json_result is
  Null -> Error("Provide an Array and not Null")
  Object(hash_map) -> hash_map.items  # `.` on hash maps returns Result
  Array(items) -> Ok(items)
  _ -> Error("Provide an Array and not a primitive value")

items_total_price = Result:map(items_result,
    items -> items
      & List:map(item -> item.price & Result:withDefault(0))
      & List:sum
  )

# Final expression must be a `Result`
# - `Error`: E.g. printed to stderr, shown as cell error, …
# - `Ok`: E.g. printed to stdout (`Json` is automatically stringified),
#         shown as cell content, …
items_result
  & Result:map(items ->
      items & List:map(item ->
        item.price
          & Result:map(price -> price / items_total)
      )
    )

Instead of threading the errors through the whole program, this can also be simplified to:

---
description: Convert item prices from € to % of total price
tags: [json]
---

json_result = $parse_json($input)

items = when json_result is
  Array(items) -> items
  Null -> $stop(Error("Provide an Array and not Null"))
  Object(hash_map) -> $stop_error(hash_map.items)  # `.x` returns Result
  _ -> stop(Error("Provide an Array and not a primitive value"))

items_total_price = items
  & List:map(item -> item.price & Result:withDefault(0))
  & List:sum

Ok(items & List:map(item ->
  item.price & Result:map(price ->
    price / items_total_price
  )
))

Related

Alternative Programming Languages

Deal-breakers are marked with a ✋.

• PRQL

  • Pipelined Relational Query Language
  • Compiles to SQL

• Numbat (Rust)

  • Statically typed
  • For scientific computations
  • First class support for physical dimensions and units
  • ✋ No support for including external data

• Roc (Rust)

  • Statically typed
  • ✋ Side effects