std

deep_seq : forall a. Dyn -> a -> a

deep_seq x y forces a deep evaluation x, before returning y. Deep evaluation means deep_seq recursively forces the evaluation of the content of records and arrays, as opposed to std.seq.

Examples

std.deep_seq (42 / 0) 37
  => error
std.deep_seq (42 / 2) 37
  => 37
std.deep_seq [1+1, { not_too_far = [42 / 0] }] 37
  => error

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deserialize : [| 'Json, 'Toml, 'Yaml |] -> String -> Dyn

Deserializes a string into a Nickel value from the given representation.

Examples

deserialize 'Json "{ \"hello\": \"Hello\", \"world\": \"World\" }"
  { hello = "Hello", world = "World" }

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fail_with | String -> Dyn

Abort the evaluation with the given message. The error will be reported as a contract violation, as fail_with uses std.FailWith under the hood.

Examples

std.fail_with "message"
  => error: contract broken by a value: message

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FailWith

A contract that always fails with the given message.

Examples

1 | std.FailWith "message"
  => error: contract broken by a value: message

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hash : [| 'Md5, 'Sha1, 'Sha256, 'Sha512 |] -> String -> String

Hashes the given string with the desired hashing algorithm.

Examples

std.hash 'Md5 "hunter2"
  => "2ab96390c7dbe3439de74d0c9b0b1767"

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is_array : Dyn -> Bool

Checks if a value is an array.

Examples

std.is_array [ 1, 2 ]
  => true
std.is_array 42
  => false

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is_bool : Dyn -> Bool

Checks if a value is a bool.

Examples

std.is_bool false
  => true
std.is_bool 42
  => false

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is_enum : Dyn -> Bool

Checks if a value is an enum tag.

Examples

std.is_enum true
  => false
std.is_enum `false
  => true

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is_function : Dyn -> Bool

Checks if a value is a function.

Examples

std.is_function (fun x => x)
  => true
std.is_function 42
  => false

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is_number : Dyn -> Bool

Checks if a value is a number.

Examples

std.is_number 1
  => true
std.is_number "Hello, World!"
  => false

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is_record : Dyn -> Bool

Checks if a value is a record.

Examples

std.is_record [ 1, 2 ]
  => false
std.is_record { hello = "Hello", world = "World" }
  => true

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is_string : Dyn -> Bool

Checks if a value is a string.

Examples

std.is_string true
  => false
std.is_string "Hello, World!"
  => true

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seq : forall a. Dyn -> a -> a

seq x y forces the evaluation of x, before returning y.

The evaluation of x stops as soon as a so-called weak head normal form is reached, which is either:

• an array
• a record
• a function (or a match statement, which is function in disguise)
• a constant (a number, a boolean, a string literal or an enum tag)
• a contract label

Note that seq won't evaluate the content of arrays and records further. Please see std.deep_seq to recursively force the evaluation of an expression.

Examples

std.seq (42 / 0) 37
  => error
std.seq (42 / 2) 37
  => 37
std.seq { too_far = 42 / 0 } 37
  => 37

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serialize : [| 'Json, 'Toml, 'Yaml |] -> Dyn -> String

Serializes a value into the desired representation.

Examples

serialize 'Json { hello = "Hello", world = "World" } =>
  "{
    \"hello\": \"Hello\",
    \"world\": \"World\"
  }"

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to_string | std.string.Stringable -> String

Converts a stringable value to a string representation. Same as std.string.from.

Examples

std.to_string 42 =>
  "42"
std.to_string 'Foo =>
  "Foo"
std.to_string null =>
  "null"

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trace : forall a. String -> a -> a

std.trace msg x prints msg to standard error, then proceeds with the evaluation of x.

Examples

std.trace "Hello, world!" true
  std.trace: Hello, world!
  => true

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typeof : Dyn -> [| '"Number", '"Bool", '"String", 'Enum, 'Label, 'Function, '"Array", 'Record, 'Other |]

Returns the type of a value.

Examples

std.typeof [ 1, 2 ]
  => 'Array
std.typeof (fun x => x)
  => 'Function

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