The Daml Cheat Sheet

Question 1

Fill in the blanks:

“Daml is an open-source _ _ _
designed to build composable applications
on an _ _ _.”

Answer 1

“… smart contract language…
… an abstract ledger model.”

Question 2

Fill in the blanks:

“Daml is a high-level language
that focuses on _ _ and _ of distributed applications.”

Answer 2

“… data privacy and authorization …”

Question 3

True or False?

Daml is a statically-typed
functional language?

Answer 3

True

Question 4

What Daml concept is this?

A person or legal entity that can create contracts and exercise choices.

Answer 4

Party

A built-in data type in Daml.

Question 5

What are four roles that a party can have on a contract?

Answer 5

1. Signatory
2. Observer
3. Controller
4. Maintainer

Roles apply to instances of the Party type.

Question 6

Fill in the blank:

“Contracts are created from blueprints called _.”

Answer 6

… templates.”

This is the Daml code you write.

Question 7

Daml templates include what three elements?

Answer 7

1. Contract data
2. Authorization
3. Choices

Question 8

True or false?

Once a contract is created, its data can be changed by a choice.

Answer 8

False

Contracts are immutable.

Question 9

Fill in the blanks:

“Every contract is a template instance stored as a _ on the _.”

Answer 9

… entry on the ledger.

Question 10

What Daml concept is this?

The action that a party can take on a contract.

Answer 10

Choice

Question 11

True or False?

Choices can archive the current contract and create a new version of the contract, with updated contract data.

Answer 11

True

Contracts are immutable.

Question 12

Fill in the blank:

“A choice can only be exercised by its _”

Answer 12

“… controller.”

Question 13

Fill in the blanks:

“A choice contains the authorization of:
1. all of the _ and
2. the _ .

(what two sets of parties?)

Answer 13

1. all of the signatories, and
2. the controller.

Question 14

What Daml concept is this?

The database where all contracts are recorded.

Answer 14

Ledger

Question 15

Daml Assistant command

Create a Daml project

Answer 15

daml new <myproject>

Question 16

Daml Assistant command

Create a Daml/React full stack project

Answer 16

daml create-daml-app <TARGET PATH>

Question 17

Daml Assistant command

Start the IDE

Answer 17

daml studio

Launches Visual Studio Code and the Daml extension

Question 18

Daml Assistant command

Compile the DAML models into a DAR file

Answer 18

daml build

Question 19

Daml Assistant command

Launch the sandbox ledger and JSON-API

Answer 19

daml start

Also builds the project

Question 20

Daml Assistant command

Launch the sandbox ledger

in wall-clock time-mode

Answer 20

daml sandbox

Question 21

Daml Assistant command

Launch the sandbox ledger

in static time-mode

Answer 21

daml sandbox --static-time

Question 22

Daml Assistant command

Launch the JSON-API server

requires a running ledger

Answer 22

daml json-api

--ledger-host localhost --ledger-port 6865 --http-port 7575

Question 23

Daml Assistant command

Upload a DAR to the ledger

Answer 23

daml ledger upload-dar <mydarfile>

Question 24

Daml Assistant command

Run the test scripts

in the current project

Answer 24

daml test

Question 25

# Daml Assistant command Run the test scripts | in a specific file

Answer 25

`daml test --files MyTests.daml`

Question 26

# Daml Assistant command Run the test scripts | in the current project *and dependencies*

Answer 26

`daml test --all`

Question 27

# Daml Assistant command What is the name of the *project configuration file*?

Answer 27

`daml.yaml`

Question 28

# Daml basics What is the *end-of-line* comment delimiter?

Answer 28

two hyphens | `let i = 1 -- This is a comment`

Question 29

# Daml basics What are the delimiters for *surrounding* comments?

Answer 29

curly brace and hyphen | `{- This is another comment -}`

Question 30

# Daml basics What does *every* Daml file start with?

Answer 30

a module header `module MyModule where` | Module name must be capitalized and match the file name.

Question 31

# Daml types How is the *type* of a *variable* specified? | For example, `myVar` is of type `TypeName`

Answer 31

`myVar : TypeName`

Question 32

# Daml types What four types represent *numbers*?

Answer 32

1. `Int` 2. `Numeric n` 3. `Decimal` 4. `BigNumeric` | `BigNumeric` is not serializable; `Decimal` is `Numeric 10`

Question 33

# Daml types What is the type for *a string of characters*?

Answer 33

`Text`

Question 34

# Daml types What is the type for *True and False values*?

Answer 34

`Bool`

Question 35

# Daml types What is the type for *a person or entity* involved in a contract?

Answer 35

`Party`

Question 36

# Daml types What are the three *date and time* types?

Answer 36

1. `Date` 2. `Time` 3. `RelTime`

Question 37

# Daml types Define a *type synonym*. | For example, `MyInt` is a synonym for `Int`

Answer 37

`type MyInt = Int`

Question 38

# Daml types Define a *type synonym for a list*. | For example, a list of `Int`s.

Answer 38

`type ListOfInts = [Int]`

Question 39

# Daml types Define a *type synonym for a tuple*. | For example, a tuple of an `Int` and `Text`

Answer 39

`type MyTuple = (Int, Text)`

Question 40

# Daml types Define a *polymorphic type*. | For example, a list of tuples of types `a` and `b`

Answer 40

`type MyType a b = [(a, b)]`

Question 41

# Daml data What is the *keyword* used to define record, product, and sum types?

Answer 41

`data`

Question 42

# Daml data Define a record. | For example, for an `Int` and `Text`

Answer 42

``` data MyRecord = MyRecord { label1: Int, label2: Text } ``` | fields must have lower-case labels

Question 43

# Daml data Define a product type. | For example, for an `Int` and `Text`

Answer 43

``` data IntAndText = IntAndText with label1:Int label2:Text ```

Question 44

# Daml data Define a sum type. | For example, for an `Int` or `Text`

Answer 44

``` data IntOrText = MyInt Int | MyText Text ``` | case names must be upper case

Question 45

# Daml data Define a record with type parameters. | AKA: "generic" or "polymorphic" record.

Answer 45

``` data MyRecord a b = MyRecord { label1: a, label2: b } ```

Question 46

# Daml data Define a record with Show/Eq instances.

Answer 46

``` data MyRecord = MyRecord { label1: Int, label2: Text } deriving (Show, Eq) ```

Question 47

# Daml functions Specify a function signature. | For example, a function takes two `Text` arguments and returns `Text`

Answer 47

`f : Text -> Text -> Text`

Question 48

# Daml functions Define a function. | For example, concatenate two strings with a space

Answer 48

`f x y = x <> " " <> y`

Question 49

# Daml functions Define a lambda. | For example, concatenate two strings

Answer 49

`\x y -> x <> y`

Question 50

# Daml functions In this polymorphic function signature, what does the `=>` follow? | `f : (Show a, Eq a) => a -> Text -> Text`

Answer 50

The type constraints | on the type parameter `a`

Question 51

# Daml functions Apply a function. | For example, `f : Text -> Text -> Text`

Answer 51

`f "Hello" "World"` | "Hello World"

Question 52

# Daml functions Partially apply a function. | For example, `f : Text -> Text -> Text`

Answer 52

salute = f "Hello" | salute : Text -> Text

Question 53

# Daml functions Specify a function signature with a *function* as an argument. | For example, `apply salute "John" -- "Hello John"`

Answer 53

`apply : (Text -> Text) -> Text -> Text`

Question 54

# Daml templates What is the keyword for beginning the blueprint of a contract?

Answer 54

`template` ``` template MyData with party : Party where signatory party ```

Question 55

# Daml templates What is the keyword for listing the data that will be stored?

Answer 55

`with` ``` template MyData with party : Party where signatory party ```

Question 56

# Daml templates What is the keyword for listing visibility, roles, choices?

Answer 56

`where` ``` template MyData with party : Party where signatory party ```

Question 57

# Daml templates What keyword identifies the party authorizing the contract?

Answer 57

`signatory` ``` where signatory party1 ```

Question 58

# Daml templates What keyword identifies a party with visibility to the contract?

Answer 58

`observer` ``` where observer party2 ```

Question 59

# Daml templates What keyword specifies a primary index for the contract?

Answer 59

`key` ``` where key dataKey : (Party, Text) ```

Question 60

# Daml templates What keyword identies a party guaranteeing uniqueness of contract keys?

Answer 60

`maintainer` ``` where maintainer key._1 ```

Question 61

# Contract keys When a contract is updated, what identifier changes and what identifier stays the same?

Answer 61

_Contract keys_ stay the same. _Contract ids_ change.

Question 62

# True or False? Contract keys on a template are optional.

Answer 62

True

Question 63

# True or False? Contract keys can be specified without a maintainer.

Answer 63

False

Question 64

# True or False? The contract key must _not_ include a contract id.

Answer 64

True

Question 65

# True or False? The contract key _must_ include all maintainer parties.

Answer 65

True

Question 66

# True or False? The choices of a contract template specify the rules on how and by whom contract data can be changed.

Answer 66

True

Question 67

# Daml choices If a choice is "consuming" what does that imply?

Answer 67

Trying to exercise another choice on the same contract id will fail.

Question 68

# Daml choices If a choice is "nonconsuming" what does that imply?

Answer 68

More choices can be subsequently exercised.

Question 69

# Daml choices Choices are *what* by default? | Consuming or nonconsuming?

Answer 69

Consuming

Question 70

# Daml choices What is the keyword for defining an action that can be exercised on a contract?

Answer 70

`choice` ``` where nonconsuming choice NameOfChoice : () with ```

Question 71

# Daml choices What is the keyword for listing the choice arguments?

Answer 71

`with` ``` nonconsuming choice NameOfChoice : () with party1 : Party party2 : Party ```

Question 72

# Daml choices What is the keyword for listing the parties that are required to execute a choice?

Answer 72

`controller` ``` nonconsuming choice NameOfChoice : () with party : Party controller party do ``` |

Question 73

# Daml choices What is the keyword for the block of code that executes?

Answer 73

`do` ``` controller party do assert (i == 42) return () ```

Question 74

# Daml updates Where are *update* expressions listed? | Choices or scripts?

Answer 74

In a choice body | Usually along with other expressions in a `do` block

Question 75

# Daml updates What is the *update expression* to create an instance of the given template on the ledger? | For example, `NameOfTemplate` and `exampleParameter` inputs

Answer 75

`create NameOfTemplate with exampleParameters`

Question 76

# Daml updates What is the *update expression* to exercise a choice on a given contract by contract id? | For example, `idOfContract`, `NameOfChoice`, `choiceArgument1 = value1`

Answer 76

`exercise idOfContract NameOfChoice with choiceArgument1 = value1`