Scrapscript

A exploration (read: very incomplete implementation) of Scrapscript.

Installation

With Go installed, run go install github.com/Victorystick/scrapscript/cmd/scrap.

Overview

The aim is to implement Scrapscript along with the scrap CLI as documented on https://scrapscript.org/guide.

So far it supports

• scrap eval to evaluate a script passed over standard input.

• scrap eval apply '...' works like scrap eval but passes the result of the former to the function defined by '...'. For example:

  $ echo '0' \
      | scrap eval apply 'n -> n + 1' \
      | scrap eval apply 'n -> n + 1' \
      | scrap eval apply 'n -> n + 1'

• scrap type to infer the type of a script passed over standard input.

  $ echo 'list/fold 0 (total -> text -> total + text/length text)' | scrap type
  list text -> int

• scrap test to run the test cases of a script passed over standard input, made with lib/test.scrap and grouped in records and lists. It prints each failing case and exits with status 1 if any failed.

  $ cd lib && printf '{ adds = t.eq (1 + 1) 3 }\n; t = $"./test.scrap"' | scrap test
  FAIL adds
      got  2
      want 3
  1 failed, 0 passed

• --root dir reads the script as if it were a file in dir, which relative imports such as $"./test.scrap" resolve from, and --cache dir keeps fetched scraps in dir instead of the user cache directory. Flags go before or after the command:

  $ scrap eval --root ./lib --cache ./tmp-scraps < some.scrap

Missing

• scrap flat - due to a lack of details.

• scrap yard - just TODO.

Note: Scraps are currently fetched from the scrapyard at https://scraps.oseg.dev/ as text and cached locally.

Differences from https://scrapscript.org

• Refers to scraps as $source:<hex>, the sha256 of their source, instead of $sha1~~…, as SHA-1 is cryptographically weak and ~~ otherwise means base64. During development, $"./path" refers to a draft file.

• No attempt to implement Scrap Maps, Scrap passes or Scrapbooks.