How can I pretty-print a Michelson contract in JSON to concrete syntax?

  • 1
    This is done by the SmartPy.io/dev explorer. We could extract the code if you need it or integrate it in the CLI.
    – FFF
    Mar 6, 2020 at 2:45

2 Answers 2


With PyTezos it would be (don't mind the naming, it is wrong, will be fixed at some point):

>>> from pytezos.michelson.converter import micheline_to_michelson
>>> print(micheline_to_michelson({'prim': 'pair', 'args': [{'string': 'hello'}, {'int': '42'}]}))
pair "hello" 42

Edit: I realized that I misread the question and answered it for Michelson to Micheline when you wanted Micheline to Michelon. I do not know if there is a way to do that via the command line. Regardless, it would be nice to have both supported by the tezos-client tool.

Michelson to Micheline

It would be nice if there was a dedicated tezos-client command to do this, but as far as I know there is not. This is what I usually do.

tezos-client -l typecheck script michelson.tz > micheline.json 2>&1

There will be some none json details in micheline.json that need to be removed.

This is an even bigger problem if you want to translate a lambda in Michelson to Micheline to use it in a Tezos library that only knows how to handle JSON. My current work around is to dry run the lambda in the contract that is going to use it.

tezos-client transfer 0 from alice to aliceLimit --entrypoint 'do' --arg '{DROP; PUSH address "KT1HWN9KL97fo7oYZgy36Je7ZYZAY6Xt4ye2"; CONTRACT %transfer (pair (pair address address) nat); IF_SOME {PUSH mutez 0; PUSH nat 100; PUSH address "tz1boB5GrcAVRtjQQLrpjM4Xpp1E438La4Wn"; PUSH address "KT1Etn69GyqDCAhZp7wY21s4Y8HefH2ujrSf"; PAIR; PAIR; TRANSFER_TOKENS;} {PUSH string ""; FAILWITH;}}' --dry-run > lambda.json 2>&1

If it succeeds you can delete the extra details from the file. There will be a lot of other unrelated things in there.

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