This Changelog only applies to notable changes of language related features in `helios.js` on the main branch.

# 2024/09/21

 - addition of `Map.to_list[T]()`

# 2023/09/12

-   cleanup of IR simplication (might change some script hashes)
-   StakeKeyHash replaced by PubKeyHash everywhere (has almost exactly the same functionality, so makes little sense for it to be a different type)

# 2023/05/21

-   Generic typing for functions, enums and structs
-   `map.update` and `map.update_safe`
-   `const` statements always require typing, but value is optional (throws error if value is unset before compilation)
-   `Any`, `<empty>` and `Valuable` typeclasses
-   `[]Int.sum`, `[]Real.sum`, `[]String.join`, `[]ByteArray.join`, `[][]ItemType.flatten`

# 2023/04/29

-   `List.drop`, `.take`, `.drop_end` and `.take_end` implemented

# 2023/04/27

-   `Real` fixed point number type with most basic math operators
-   auto-set tx validity time_range if tx.time_range is called in any of the scripts

# 2023/04/25

-   `List.get_singleton()`
-   Destructuring enum instances into enum variants throws runtime errors instead of compile-time errors

# 2023/04/13

-   `Int` methods: `abs`, `encode_zigzag`, `decode_zigzag`, `to_little_endian`, `to_big_endian`, `to_base58`
-   `Int::from_big_endian` and `from_base58` associated functions
-   `ByteArray.prepend`

# 2023/04/12

-   Destructuring syntax for assignments and for switch cases

# 2023/04/10

-   `Duration::SECOND`, `MINUTE`, `HOUR`, `DAY`, `WEEK`

# 2023/04/03

-   `AssetClass.mph` and `AssetClass.token_name`

# 2023/03/27

-   `TimeRange.show`

# 2023/03/13

-   Functions can have optional arguments
-   `Value.show`
-   `copy` automatically defined on all user structs and user enum variants

# 2023/03/06

-   Addition of `ctx.get_cont_outputs()`
-   Addition of `value.get_assets()`
-   Addition of `option.map()`

# 2023/03/05

-   Addition of `Map.for_each`
-   Addition of `Int::min`, `Int::max`, `int.bound()`, `int.bound_min()`, `int.bound_max()`
-   Addition of `tx.get_datum_data(output: TxOutput)`
-   Addition of `Value.get_lovelace()`

# 2023/02/17

-   Addition of `Data.tag`
-   Addition of `List.for_each()`

# 2023/01/18

-   IR: Removed simplify calls from inline methods. Slight decrease in optimization performance, huge increase in compiler speed.

# 2023/01/11

-   TxId, TxOutputId and hash-type comparison operators and `show`
-   Functions can return void `()` by using `print`, `error` or `assert` as final expressions
-   Function expressions return type is optional `(...) -> {...}`
-   `OutputDataum.inline_data`
-   `Address::new_empty`
-   `Wallet`, `Cip30Wallet`, `WalletHelper`, `Network` and `BlockfrostV0` for interacting with browser wallets and the blockchain
-   `CoinSelection` class with static method `pickSmallest`
-   `HeliosData` instances which can be assigned directly to `Program.parameters`
-   Builtin `HeliosData` types: `Int`, `Bool`, `ByteArray`, `HeliosString`, `Address`, `TxId`, hash-types, `Time`, `Duration`, `TxOutputId`, `Value`
-   Builtin `List`, `HeliosMap` and `Option` `HeliosData`-type generators.
-   Helios structs and enums are avaible as `HeliosData` types through `program.types`

# 2022/12/21

-   Addition of `Map.prepend`
-   Addition of comparisons for ByteArray: `<`, `>`, `<=` and `>=`
-   Function definitions can ignore (all but one) argument with `_`
-   Functions can returns multiple values, assignments can assign multi-value rhs to multiple variables (not `const` though), and multi-value expressions are automatically flattened when used in a call

# 2022/12/18

-   Addition of `Map.delete`, `Map.set`, `Map.find`, `Map.find_by_key`, `Map.find_by_value`
-   Addition of `Map.head_key`, `Map.head_value`, `Map.tail`

# 2022/12/17

-   Addition of `List.fold_lazy`, `Map.fold_lazy`, `Map.fold_keys_lazy`, `Map.fold_values_lazy`
-   Printing of messages when redemption computation throws an error

# 2022/12/13

-   Addition of `List.sort`
-   Addition of `StakingHash::Validator.hash` and `StakingHash::StakeKey.hash`
-   Addition of `Map.find_key`, `Map.find_key_safe`, `Map.find_value`, `Map.find_value_safe`
-   Addition of `Map.sort`, `Map.sort_by_key`, `Map.sort_by_value`

# 2022/12/12

-   Addition of `Value.get_safe`.

# 2022/12/10

-   Addition of `ScriptHash`, `StakingHash`, `StakingHash::StakeKey`, `StakingHash::Validator`, `StakeKeyHash`, `StakingValidatorHash` (on-chain)
-   `TxOutput.ref_script_hash -> Option[ScriptHash]` getter (on-chain)
-   `(ValidatorHash|MintingPolicyHash|StakingValidatorHash).from_script_hash()` (on-chain)
-   Addition StakeAddress, StakeKeyHash and StakingValidatorHash (off-chain)
-   Address construction distinguishes between StakeKeyHash and StakingValidatorHash

# 2022/12/08

-   `Value.to_map()`

# 2022/12/03

-   Switch expression works over Data
-   Type inference for literal enum member constructors that have zero fields
-   `PubKey` builtin type, and `PubKey.verify` method (aka verifyEd25519Signature)

# 2022/11/25

-   Structs with 1 field are represented directly by their contained field in Uplc
-   Structs with more than 1 field are represented as a list of data in Uplc (no longer as ConstrData)
-   IR functions with zero arguments become Delay terms in Uplc
-   IR calls with zero arguments become Force terms in Uplc
-   Core cast functions are extracted as high up as possible
-   Special syntax for throwing errors inside switch/if-else branches: `error("...")`

# 2022/11/22

-   Added `Int::from_little_endian()`

# 2022/11/20

-   Added `Value.contains_policy()` method

# 2022/11/06

-   Modules functionality with `import`

# 2022/10/30

-   Added `TxRefInput` export

# 2022/10/27

-   Added `new` constructor for `ScriptPurpose` members
-   Added list.`find_safe` method

# 2022/10/26

-   `redeemers` field added to `Tx::new` constructor

# 2022/10/25

-   Better error message when catching `RuntimeError` inside `evalParam`

# 2022/10/23

-   HashedDatum and InlineDatum no longer exported
-   TxId and DatumHash exported, `Hash` no longer exported
-   changeParam handles Hash type literals

# 2022/10/21

-   ScriptPurpose type, with members Minting, Spending, Rewarding and Certifying
-   `ScriptContext.get_script_purpose()`
-   `Tx.redeemers`
-   `Int::parse`
-   unused struct/enum fields, and unused enum variants, are now allowed
-   `Option.unwrap()`

# 2022/10/11

-   added `Value::from_map`
-   removed `tx.now()` (in favor of `tx.time_range.start` and `tx.time_range.end`)
-   changed `time_range.get_start()` to `time_range.start` (is a getter!)
-   added `time_range.end` (is a getter!)
-   added `map.map_keys()` and `map.map_values()`
-   support for operator overloading (internally), with `Time - Duration -> Time` and `Duration/Duration -> Int` as new overloads
-   `+` and `*` operators are now commutative in case left and right types differ

# 2022/09/19

-   toSchemaJSON renamed to toSchemaJson
-   tx.outputs_sent_to_datum, tx.value_sent_to_datum, tx.outputs_locked_by_datum, tx.value_locked_by_datum: now take 'isInline' as a third boolean argument

# 2022/09/16

-   PlutusCore renamed to UPLC everywhere
-   helios.d.ts file generated

# 2022/08/26

-   program.changeParam accepts both jsons strings and PlutusCoreValue is value

# 2022/08/25

-   `[]a.new` method uses `func(Int) -> a` as second arg (first arg is length), List.new_const introduced that uses `a` as second arg (first arg is length).

# 2022/08/22

-   TxOutput can have inline datum
-   TxOutput.datum returns OutputDatum enum (replaces the .datum_hash field)
-   OutputDatum enum has members None, Hash and Inline
-   generic Data type introduced (used by inline datum)
-   All types have builtin associated ::from_data() method that converts `Data` into that type
-   Map.get_safe() method that returns Option
-   staking script purpose
-   StakingPurpose enum, with members Rewarding and Certifying, returned by ScriptContext.get_staking_purpose() (only available in staking/testing script)
-   DCert enum with members Register, Deregister, Delegate, RegisterPool, RetirePool (DCertGenesis and DCertMir ignored)
-   New fields for Tx: Tx.ref_inputs, Tx.dcerts and Tx.withdrawals (constructor for Tx also changed accordingly)
-   ScriptContext constructors have been renamed: new_spending, new_minting, new_rewarding and new_certifying

# 2022/08/19

-   Library interface changed to something more object-like
-   Script purpose keywords changed to 'testing', 'spending' and 'minting'
-   Macro-like builtins whichs are only allowed after 'main': ValidatorHash::CURRENT, MintingPolicyHash::CURRENT, ScriptContext::new, Tx::new, TxID::CURRENT, TxInput::new, TxOutput::new
-   Generally usable constructors: TxId::new, Address::new, Credential::new_pubkey, Credential::new_validator, StakingCredential::new_hash, StakingCredential::new_ptr
-   First argument of AssetClass::new must be MintingPolicyHash (was ByteArray previously)

# 2022/08/17

-   Cost calculation of a plutus-core program run

# 2022/08/16

-   'simplify' boolean flag in config object that is passed to compile()
-   Map key can't be bool type (makes it easier to use bool as primitive in plutus-core, instead of as data type)
-   `Value*Int` (not commutative) and `Value/Int` operators
-   tx methods: 'outputs_sent_to_datum', 'outputs_locked_by_datum' and 'value_sent_to_datum' (not yet property tested)

# 2022/08/11

-   ByteArray.slice (negative indices relative to end)
-   ByteArray starts_with and ends_with
-   String starts_with and ends_with
-   Map + Map operator (note: map merge doesn't assert uniqueness of keys and simply acts as a concatenation of two lists)
-   Map methods: all, all_keys, all_values, any, any_key, any_value, filter, filter_by_key, filter_by_value, fold, fold_keys, fold_values
-   all methods named 'get...' or 'find...' throw errors if not found
-   TokenName in AssetClass is now ByteArray in order to align with Plutus-Ledger-API (used to be String)

# 2022/08/10

-   Rust-like syntax, structs and enums can have methods
-   No commas in struct/enum-member definitions
-   No semicolon after const statement
-   C#-like switch syntax
-   TimeRange constructors: ALWAYS, NEVER, from, to
-   TimeRange comparison: is_before(Time) and is_after(Time)
-   Map literal construction, Map.length, Map.is_empty() and Map.get()
-   Value.get_policy()

# 2022/07/15

-   renamed to helios

## 2022/07/09

-   all named variables in the Plutus-Light are prefixed with u\_ when generating the untyped IR