Built-in Functions
General
CHARSET_ASCII
Constant denoting the ASCII charset
Constant: CHARSET_ASCII:integer = 0
CHARSET_LATIN1
Constant denoting the Latin-1 charset ISO-8859-1
Constant: CHARSET_LATIN1:integer = 1
at
idx integer
list [<l>]
→ <a>
idx string
object object:<{o}>
→ <a>
Index LIST at IDX, or get value with key IDX from OBJECT.
pact> (at 1 [1 2 3])2pact> (at "bar" { "foo": 1, "bar": 2 })2
pact> (at 1 [1 2 3])2pact> (at "bar" { "foo": 1, "bar": 2 })2
base64-decode
string string
→ string
Decode STRING from unpadded base64
pact> (base64-decode "aGVsbG8gd29ybGQh")"hello world!"
pact> (base64-decode "aGVsbG8gd29ybGQh")"hello world!"
base64-encode
string string
→ string
Encode STRING as unpadded base64
pact> (base64-encode "hello world!")"aGVsbG8gd29ybGQh"
pact> (base64-encode "hello world!")"aGVsbG8gd29ybGQh"
bind
src object:<{row}>
binding binding:<{row}>
→ <a>
Special form evaluates SRC to an object which is bound to with BINDINGS over subsequent body statements.
pact> (bind { "a": 1, "b": 2 } { "a" := a-value } a-value)1
pact> (bind { "a": 1, "b": 2 } { "a" := a-value } a-value)1
chain-data
→ object:{public-chain-data}
Get transaction public metadata. Returns an object with 'chain-id', 'block-height', 'block-time', 'prev-block-hash', 'sender', 'gas-limit', 'gas-price', and 'gas-fee' fields.
pact> (chain-data){"block-height": 0,"block-time": "1970-01-01T00:00:00Z","chain-id": "","gas-limit": 0,"gas-price": 0.0,"prev-block-hash": "","sender": ""}
pact> (chain-data){"block-height": 0,"block-time": "1970-01-01T00:00:00Z","chain-id": "","gas-limit": 0,"gas-price": 0.0,"prev-block-hash": "","sender": ""}
compose
x x:<a> -> <b>
y x:<b> -> <c>
value <a>
→ <c>
Compose X and Y, such that X operates on VALUE, and Y on the results of X.
pact> (filter (compose (length) (< 2)) ["my" "dog" "has" "fleas"])["dog" "has" "fleas"]
pact> (filter (compose (length) (< 2)) ["my" "dog" "has" "fleas"])["dog" "has" "fleas"]
concat
str-list [string]
→ string
Takes STR-LIST and concats each of the strings in the list, returning the resulting string
pact> (concat ["k" "d" "a"])"kda"pact> (concat (map (+ " ") (str-to-list "abcde")))" a b c d e"
pact> (concat ["k" "d" "a"])"kda"pact> (concat (map (+ " ") (str-to-list "abcde")))" a b c d e"
constantly
value <a>
ignore1 <b>
→ <a>
value <a>
ignore1 <b>
ignore2 <c>
→ <a>
value <a>
ignore1 <b>
ignore2 <c>
ignore3 <d>
→ <a>
Lazily ignore arguments IGNORE* and return VALUE.
pact> (filter (constantly true) [1 2 3])[1 2 3]
pact> (filter (constantly true) [1 2 3])[1 2 3]
contains
value <a>
list [<a>]
→ bool
key <a>
object object:<{o}>
→ bool
value string
string string
→ bool
Test that LIST or STRING contains VALUE, or that OBJECT has KEY entry.
pact> (contains 2 [1 2 3])truepact> (contains 'name { 'name: "Ted", 'age: 72 })truepact> (contains "foo" "foobar")true
pact> (contains 2 [1 2 3])truepact> (contains 'name { 'name: "Ted", 'age: 72 })truepact> (contains "foo" "foobar")true
continue
value *
→ *
Continue a previously started nested defpact.
(continue (coin.transfer-crosschain "bob" "alice" 10.0))
(continue (coin.transfer-crosschain "bob" "alice" 10.0))
define-namespace
namespace string
user-guard guard
admin-guard guard
→ string
Create a namespace called NAMESPACE where ownership and use of the namespace is controlled by GUARD. If NAMESPACE is already defined, then the guard previously defined in NAMESPACE will be enforced, and GUARD will be rotated in its place.
(define-namespace 'my-namespace (read-keyset 'user-ks) (read-keyset 'admin-ks))
(define-namespace 'my-namespace (read-keyset 'user-ks) (read-keyset 'admin-ks))
Top level only: this function will fail if used in module code.
describe-namespace
ns string
→ object:{described-namespace}
Describe the namespace NS, returning a row object containing the user and admin guards of the namespace, as well as its name.
(describe-namespace 'my-namespace)
(describe-namespace 'my-namespace)
Top level only: this function will fail if used in module code.
distinct
values [<a>]
→ [<a>]
Returns from a homogeneous list of VALUES a list with duplicates removed. The original order of the values is preserved.
pact> (distinct [3 3 1 1 2 2])[3 1 2]
pact> (distinct [3 3 1 1 2 2])[3 1 2]
drop
count integer
list <a[[<l>],string]>
→ <a[[<l>],string]>
keys [string]
object object:<{o}>
→ object:<{o}>
Drop COUNT values from LIST (or string), or entries having keys in KEYS from OBJECT. If COUNT is negative, drop from end. If COUNT exceeds the interval (-2^63,2^63), it is truncated to that range.
pact> (drop 2 "vwxyz")"xyz"pact> (drop (- 2) [1 2 3 4 5])[1 2 3]pact> (drop ['name] { 'name: "Vlad", 'active: false}){"active": false}
pact> (drop 2 "vwxyz")"xyz"pact> (drop (- 2) [1 2 3 4 5])[1 2 3]pact> (drop ['name] { 'name: "Vlad", 'active: false}){"active": false}
enforce
test bool
msg string
→ bool
Fail transaction with MSG if pure expression TEST is false. Otherwise, returns true.
pact> (enforce (!= (+ 2 2) 4) "Chaos reigns")<interactive>:0:0:Error: Chaos reigns
pact> (enforce (!= (+ 2 2) 4) "Chaos reigns")<interactive>:0:0:Error: Chaos reigns
enforce-one
msg string
tests [bool]
→ bool
Run TESTS in order (in pure context, plus keyset enforces). If all fail, fail transaction. Short-circuits on first success.
pact> (enforce-one "Should succeed on second test" [(enforce false "Skip me") (enforce (= (+ 2 2) 4) "Chaos reigns")])true
pact> (enforce-one "Should succeed on second test" [(enforce false "Skip me") (enforce (= (+ 2 2) 4) "Chaos reigns")])true
enforce-pact-version
min-version string
→ bool
min-version string
max-version string
→ bool
Enforce runtime pact version as greater than or equal MIN-VERSION, and less than or equal MAX-VERSION. Version values are matched numerically from the left, such that '2', '2.2', and '2.2.3' would all allow '2.2.3'.
pact> (enforce-pact-version "2.3")true
pact> (enforce-pact-version "2.3")true
Top level only: this function will fail if used in module code.
enumerate
from integer
to integer
inc integer
→ [integer]
from integer
to integer
→ [integer]
Returns a sequence of numbers from FROM to TO (both inclusive) as a list. INC is the increment between numbers in the sequence. If INC is not given, it is assumed to be 1. Additionally, if INC is not given and FROM is greater than TO assume a value for INC of -1. If FROM equals TO, return the singleton list containing FROM, irrespective of INC's value. If INC is equal to zero, this function will return the singleton list containing FROM. If INC is such that FROM + INC > TO (when FROM < TO) or FROM + INC < TO (when FROM > TO) return the singleton list containing FROM. Lastly, if INC is such that FROM + INC < TO (when FROM < TO) or FROM + INC > TO (when FROM > TO), then this function fails.
pact> (enumerate 0 10 2)[0 2 4 6 8 10]pact> (enumerate 0 10)[0 1 2 3 4 5 6 7 8 9 10]pact> (enumerate 10 0)[10 9 8 7 6 5 4 3 2 1 0]
pact> (enumerate 0 10 2)[0 2 4 6 8 10]pact> (enumerate 0 10)[0 1 2 3 4 5 6 7 8 9 10]pact> (enumerate 10 0)[10 9 8 7 6 5 4 3 2 1 0]
filter
app x:<a> -> bool
list [<a>]
→ [<a>]
Filter LIST by applying APP to each element. For each true result, the original value is kept.
pact> (filter (compose (length) (< 2)) ["my" "dog" "has" "fleas"])["dog" "has" "fleas"]
pact> (filter (compose (length) (< 2)) ["my" "dog" "has" "fleas"])["dog" "has" "fleas"]
fold
app x:<a> y:<b> -> <a>
init <a>
list [<b>]
→ <a>
Iteratively reduce LIST by applying APP to last result and element, starting with INIT.
pact> (fold (+) 0 [100 10 5])115
pact> (fold (+) 0 [100 10 5])115
format
template string
vars [*]
→ string
Interpolate VARS into TEMPLATE using .
pact> (format "My {} has {}" ["dog" "fleas"])"My dog has fleas"
pact> (format "My {} has {}" ["dog" "fleas"])"My dog has fleas"
hash
value <a>
→ string
Compute BLAKE2b 256-bit hash of VALUE represented in unpadded base64-url. Strings are converted directly while other values are converted using their JSON representation. Non-value-level arguments are not allowed.
pact> (hash "hello")"Mk3PAn3UowqTLEQfNlol6GsXPe-kuOWJSCU0cbgbcs8"pact> (hash { 'foo: 1 })"h9BZgylRf_M4HxcBXr15IcSXXXSz74ZC2IAViGle_z4"
pact> (hash "hello")"Mk3PAn3UowqTLEQfNlol6GsXPe-kuOWJSCU0cbgbcs8"pact> (hash { 'foo: 1 })"h9BZgylRf_M4HxcBXr15IcSXXXSz74ZC2IAViGle_z4"
identity
value <a>
→ <a>
Return provided value.
pact> (map (identity) [1 2 3])[1 2 3]
pact> (map (identity) [1 2 3])[1 2 3]
if
cond bool
then <a>
else <a>
→ <a>
Test COND. If true, evaluate THEN. Otherwise, evaluate ELSE.
pact> (if (= (+ 2 2) 4) "Sanity prevails" "Chaos reigns")"Sanity prevails"
pact> (if (= (+ 2 2) 4) "Sanity prevails" "Chaos reigns")"Sanity prevails"
int-to-str
base integer
val integer
→ string
Represent integer VAL as a string in BASE. BASE can be 2-16, or 64 for unpadded base64URL. Only positive values are allowed for base64URL conversion.
pact> (int-to-str 16 65535)"ffff"pact> (int-to-str 64 43981)"q80"
pact> (int-to-str 16 65535)"ffff"pact> (int-to-str 64 43981)"q80"
is-charset
charset integer
input string
→ bool
Check that a string INPUT conforms to the a supported character set CHARSET. Character sets currently supported are: 'CHARSET_LATIN1' (ISO-8859-1), and 'CHARSET_ASCII' (ASCII). Support for sets up through ISO 8859-5 supplement will be added in the future.
pact> (is-charset CHARSET_ASCII "hello world")truepact> (is-charset CHARSET_ASCII "I am nÖt ascii")falsepact> (is-charset CHARSET_LATIN1 "I am nÖt ascii, but I am latin1!")true
pact> (is-charset CHARSET_ASCII "hello world")truepact> (is-charset CHARSET_ASCII "I am nÖt ascii")falsepact> (is-charset CHARSET_LATIN1 "I am nÖt ascii, but I am latin1!")true
length
x <a[[<l>],string,object:<{o}>]>
→ integer
Compute length of X, which can be a list, a string, or an object.
pact> (length [1 2 3])3pact> (length "abcdefgh")8pact> (length { "a": 1, "b": 2 })2
pact> (length [1 2 3])3pact> (length "abcdefgh")8pact> (length { "a": 1, "b": 2 })2
list
elems *
→ [*]
Create list from ELEMS. Deprecated in Pact 2.1.1 with literal list support.
pact> (list 1 2 3)[1 2 3]
pact> (list 1 2 3)[1 2 3]
list-modules
→ [string]
List modules available for loading.
Top level only: this function will fail if used in module code.
make-list
length integer
value <a>
→ [<a>]
Create list by repeating VALUE LENGTH times.
pact> (make-list 5 true)[true true true true true]
pact> (make-list 5 true)[true true true true true]
map
app x:<b> -> <a>
list [<b>]
→ [<a>]
Apply APP to each element in LIST, returning a new list of results.
pact> (map (+ 1) [1 2 3])[2 3 4]
pact> (map (+ 1) [1 2 3])[2 3 4]
namespace
namespace string
→ string
Set the current namespace to NAMESPACE. All expressions that occur in a current transaction will be contained in NAMESPACE, and once committed, may be accessed via their fully qualified name, which will include the namespace. Subsequent namespace calls in the same tx will set a new namespace for all declarations until either the next namespace declaration, or the end of the tx.
(namespace 'my-namespace)
(namespace 'my-namespace)
Top level only: this function will fail if used in module code.
pact-id
→ string
Return ID if called during current pact execution, failing if not.
pact-version
→ string
Obtain current pact build version.
pact> (pact-version)"4.7.1"
pact> (pact-version)"4.7.1"
Top level only: this function will fail if used in module code.
public-chain-data
Schema type for data returned from 'chain-data'.
Fields: chain-id:string
block-height:integer
block-time:time
prev-block-hash:string
sender:string
gas-limit:integer
gas-price:decimal
read-decimal
key string
→ decimal
Parse KEY string or number value from top level of message data body as decimal.
(defun exec () (transfer (read-msg "from") (read-msg "to") (read-decimal "amount")))
(defun exec () (transfer (read-msg "from") (read-msg "to") (read-decimal "amount")))
read-integer
key string
→ integer
Parse KEY string or number value from top level of message data body as integer.
(read-integer "age")
(read-integer "age")
read-msg
→ <a>
key string
→ <a>
Read KEY from top level of message data body, or data body itself if not provided. Coerces value to their corresponding pact type: String -> string, Number -> integer, Boolean -> bool, List -> list, Object -> object.
(defun exec () (transfer (read-msg "from") (read-msg "to") (read-decimal "amount")))
(defun exec () (transfer (read-msg "from") (read-msg "to") (read-decimal "amount")))
read-string
key string
→ string
Parse KEY string or number value from top level of message data body as string.
(read-string "sender")
(read-string "sender")
remove
key string
object object:<{o}>
→ object:<{o}>
Remove entry for KEY from OBJECT.
pact> (remove "bar" { "foo": 1, "bar": 2 }){"foo": 1}
pact> (remove "bar" { "foo": 1, "bar": 2 }){"foo": 1}
resume
binding binding:<{r}>
→ <a>
Special form binds to a yielded object value from the prior step execution in a pact. If yield step was executed on a foreign chain, enforce endorsement via SPV.
reverse
list [<a>]
→ [<a>]
Reverse LIST.
pact> (reverse [1 2 3])[3 2 1]
pact> (reverse [1 2 3])[3 2 1]
sort
values [<a>]
→ [<a>]
fields [string]
values [object:<{o}>]
→ [object:<{o}>]
Sort a homogeneous list of primitive VALUES, or objects using supplied FIELDS list.
pact> (sort [3 1 2])[1 2 3]pact> (sort ['age] [{'name: "Lin",'age: 30} {'name: "Val",'age: 25}])[{"name": "Val","age": 25} {"name": "Lin","age": 30}]
pact> (sort [3 1 2])[1 2 3]pact> (sort ['age] [{'name: "Lin",'age: 30} {'name: "Val",'age: 25}])[{"name": "Val","age": 25} {"name": "Lin","age": 30}]
str-to-int
str-val string
→ integer
base integer
str-val string
→ integer
Compute the integer value of STR-VAL in base 10, or in BASE if specified. STR-VAL can be up to 512 chars in length. BASE must be between 2 and 16, or 64 to perform unpadded base64url conversion. Each digit must be in the correct range for the base.
pact> (str-to-int 16 "abcdef123456")188900967593046pact> (str-to-int "123456")123456pact> (str-to-int 64 "q80")43981
pact> (str-to-int 16 "abcdef123456")188900967593046pact> (str-to-int "123456")123456pact> (str-to-int 64 "q80")43981
str-to-list
str string
→ [string]
Takes STR and returns a list of single character strings
pact> (str-to-list "hello")["h" "e" "l" "l" "o"]pact> (concat (map (+ " ") (str-to-list "abcde")))" a b c d e"
pact> (str-to-list "hello")["h" "e" "l" "l" "o"]pact> (concat (map (+ " ") (str-to-list "abcde")))" a b c d e"
take
count integer
list <a[[<l>],string]>
→ <a[[<l>],string]>
keys [string]
object object:<{o}>
→ object:<{o}>
Take COUNT values from LIST (or string), or entries having keys in KEYS from OBJECT. If COUNT is negative, take from end. If COUNT exceeds the interval (-2^63,2^63), it is truncated to that range.
pact> (take 2 "abcd")"ab"pact> (take (- 3) [1 2 3 4 5])[3 4 5]pact> (take ['name] { 'name: "Vlad", 'active: false}){"name": "Vlad"}
pact> (take 2 "abcd")"ab"pact> (take (- 3) [1 2 3 4 5])[3 4 5]pact> (take ['name] { 'name: "Vlad", 'active: false}){"name": "Vlad"}
try
default <a>
action <a>
→ <a>
Attempt a pure ACTION, returning DEFAULT in the case of failure. Pure expressions are expressions which do not do i/o or work with non-deterministic state in contrast to impure expressions such as reading and writing to a table.
pact> (try 3 (enforce (= 1 2) "this will definitely fail"))3(expect "impure expression fails and returns default" "default" (try "default" (with-read accounts id {'ccy := ccy}) ccy))
pact> (try 3 (enforce (= 1 2) "this will definitely fail"))3(expect "impure expression fails and returns default" "default" (try "default" (with-read accounts id {'ccy := ccy}) ccy))
tx-hash
→ string
Obtain hash of current transaction as a string.
pact> (tx-hash)"DldRwCblQ7Loqy6wYJnaodHl30d3j3eH-qtFzfEv46g"
pact> (tx-hash)"DldRwCblQ7Loqy6wYJnaodHl30d3j3eH-qtFzfEv46g"
typeof
x <a>
→ string
Returns type of X as string.
pact> (typeof "hello")"string"
pact> (typeof "hello")"string"
where
field string
app x:<a> -> bool
value object:<{row}>
→ bool
Utility for use in 'filter' and 'select' applying APP to FIELD in VALUE.
pact> (filter (where 'age (> 20)) [{'name: "Mary",'age: 30} {'name: "Juan",'age: 15}])[{"name": "Juan","age": 15}]
pact> (filter (where 'age (> 20)) [{'name: "Mary",'age: 30} {'name: "Juan",'age: 15}])[{"name": "Juan","age": 15}]
yield
object object:<{y}>
→ object:<{y}>
object object:<{y}>
target-chain string
→ object:<{y}>
Yield OBJECT for use with 'resume' in following pact step. With optional argument TARGET-CHAIN, target subsequent step to execute on targeted chain using automated SPV endorsement-based dispatch.
(yield { "amount": 100.0 })(yield { "amount": 100.0 } "some-chain-id")
(yield { "amount": 100.0 })(yield { "amount": 100.0 } "some-chain-id")
zip
f x:<a> y:<b> -> <c>
list1 [<a>]
list2 [<b>]
→ [<c>]
Combine two lists with some function f, into a new list, the length of which is the length of the shortest list.
pact> (zip (+) [1 2 3 4] [4 5 6 7])[5 7 9 11]pact> (zip (-) [1 2 3 4] [4 5 6])[-3 -3 -3]pact> (zip (+) [1 2 3] [4 5 6 7])[5 7 9]pact> (zip (lambda (x y) { 'x: x, 'y: y }) [1 2 3 4] [4 5 6 7])[{"x": 1,"y": 4} {"x": 2,"y": 5} {"x": 3,"y": 6} {"x": 4,"y": 7}]
pact> (zip (+) [1 2 3 4] [4 5 6 7])[5 7 9 11]pact> (zip (-) [1 2 3 4] [4 5 6])[-3 -3 -3]pact> (zip (+) [1 2 3] [4 5 6 7])[5 7 9]pact> (zip (lambda (x y) { 'x: x, 'y: y }) [1 2 3 4] [4 5 6 7])[{"x": 1,"y": 4} {"x": 2,"y": 5} {"x": 3,"y": 6} {"x": 4,"y": 7}]