morley: Developer tools for the Michelson Language

[ language, library, mit, program ] [ Propose Tags ]

A library to make writing smart contracts in Michelson — the smart contract language of the Tezos blockchain — pleasant and effective.

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Dependencies aeson, aeson-casing, aeson-pretty, base-noprelude (>=4.7 && <5), base58-bytestring, binary, bytestring, constraints (>=0.11), containers, cryptonite, data-default, elliptic-curve, first-class-families (>=, fmt, galois-field, generic-deriving, gitrev, haskeline, hex-text, interpolate, lens, megaparsec (>=7.0.0), memory, MonadRandom, morley, morley-prelude (>=0.3.0), mtl, named, optparse-applicative, pairing, parser-combinators (>=1.0.0), scientific, semigroups (>=0.19.1), show-type, singletons, syb, template-haskell, text, text-manipulate, th-lift, th-lift-instances, time, timerep, uncaught-exception, unordered-containers, vector, vinyl, with-utf8, wl-pprint-text [details]
License MIT
Copyright 2018 camlCase, 2019-2021 Tocqueville Group
Author camlCase, Serokell, Tocqueville Group
Maintainer Serokell <>
Category Language
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Source repo head: git clone
Uploaded by pasqu4le at 2021-08-07T16:17:16Z
Distributions NixOS:1.15.1
Executables morley
Downloads 9541 total (99 in the last 30 days)
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Status Hackage Matrix CI
Docs uploaded by user [build log]
All reported builds failed as of 2021-08-07 [all 1 reports]


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Readme for morley-1.15.1

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Morley: Developer tools for the Michelson Language


Morley aims to make writing smart contracts in Michelson pleasant and effective. It contains 3 major things:

  1. An executable that lets you perform various operations on Michelson smart contracts.
  2. A library with core Tezos and Michelson data types, and functions such as Michelson typechecker and interpreter.
  3. A superset of the Michelson language that we call the Morley language. It relaxes Michelson parser rules, adds some syntax sugar and simple features.

Morley executable

How to install

There are three ways to get Morley executable:

  • Docker based (preferable).
    • Get script (e. g. using curl > and run it ./ <args>. This script will pull a docker image that contains the latest version of Morley executable from the production branch and run it with the given arguments. You'll need coreutils to be installed in order to use
    • Usage example:
      • ./ to see help message
      • ./ run --contract --storage 1 --parameter 1 --amount 1
  • Stack based.
    • Clone this git repository and run stack build command, after that you can do stack exec -- morley <args> to run morley executable built from the source code.
    • Usage example:
      • stack exec -- morley --help to see help message
      • stack exec -- morley originate --contract contracts/tezos_examples/attic/ --storage 1 --verbose
  • Cabal based.
    • Clone this git repository, go to this directory and run cabal new-update && cabal new-build command, after that you can do cabal new-run -- morley <args> to run morley executable built from the source code.
    • Usage example:
      • cabal new-run -- morley --help to see help message
      • cabal new-run -- morley originate --contract contracts/tezos_examples/attic/ --storage 1 --verbose


Morley executable does not interact with Tezos node and Tezos network. It works in emulated environment which is stored in a simple JSON file on disk. The following commands depend on environment and may modify it:

  • originate a contract.
  • transfer tokens to a given address (and call a smart contract if it's the destination).
  • run a contract. A given contract is being originated first, and then the transaction is being sent to it.

The following commands don't depend on environment:

  • optimize a contract by replacing certain sequences of instructions with equivalent but more efficient ones.
  • typecheck a contract.
  • repl starts a REPL where you can type Michelson instructions and interpret them.
  • analyze a contract and print some statistics about it.
  • print a contract in vanilla Michelson format. It can be useful in some cases:
    • You have a smart contract that uses Morley extensions and want to convert it to vanilla Michelson format that can be handled by Tezos reference implementation.
    • You have a contract with inconsistent/ugly formatting and want to format it in uniform style.
    • You want to print a contract on a single line.
  • parse a contract and return its representation in Haskell types.

You can get more info about these commands by running morley <command> --help. Run morley --help to get the list of all commands.

Morley library

Morley-the library is available on Hackage. It consists of the following parts:

Morley language

Morley-the-language is a superset of the Michelson language, which means that each Michelson contract is also a valid Morley contract but not vice versa. There are several extensions which make it more convenient to write Michelson contracts and test them. For example, one can write inline assertions in their contracts for testing. All the details can be found in the document about these extensions. A smart contract written in the Morley language can be transpiled to Michelson using the aforementioned morley print command.