Usage & API¶

The module path is github.com/go-pcore/pcore; the package is pcore.

Values¶

pcore.Value is an alias for any. Values use their natural Go types:

scalars — bool, int64, float64, string
arrays — []pcore.Value
hashes — *pcore.Hash (ordered, arbitrary keys) or a map[string]Value
the rest — wrapper types: Undef, Default, *Sensitive, *Regexp, *Binary, *Timestamp, *Timespan

A Go nil is treated as Undef; the integer and float widths are canonicalized to int64 / float64.

h := pcore.NewHash(
    pcore.HashEntry{Key: "name", Value: "puppet"},
    pcore.HashEntry{Key: "port", Value: int64(8140)},
)
secret := pcore.NewSensitive("hunter2")
fmt.Println(secret) // Sensitive[value redacted]

The type parser¶

t, err := pcore.Parse("Struct[{'name' => String, Optional['port'] => Integer[1,65535]}]")

Parse is the Go rendering of Puppet's Type(string) — Go cannot name a function and the Type interface identically, so the parser is Parse. Every Type has a canonical String() that round-trips through Parse.

Operations¶

Function	Purpose
`IsInstance(t Type, v Value) bool`	is `v` an instance of `t`?
`IsAssignable(a, b Type) bool`	is `b` a subtype of `a`?
`Infer(v Value) Type`	the most specific type of `v`
`Generalize(t Type) Type`	drop range/size constraints
`CommonType(a, b Type) Type`	narrowest supertype of both
`ToData(v Value) (Value, error)`	rich-data representation
`FromData(v Value) (Value, error)`	reconstruct from rich data

t, _ := pcore.Parse("Integer[0,10]")
pcore.IsInstance(t, int64(3)) // true

a, _ := pcore.Parse("Data")
b, _ := pcore.Parse("Array[Integer]")
pcore.IsAssignable(a, b) // true — Array[Integer] <: Data

pcore.Infer("hello")           // String[5, 5]
pcore.Generalize(pcore.Infer("hello")) // String

Constructors¶

Types can also be built programmatically without the parser: NewInteger, AnyInteger, NewFloat, AnyFloat, NewString, AnyString, NewEnum, NewArray, NewHashType, NewVariant, NewOptional, and the singleton accessors (AnyT, ScalarT, DataT, BooleanT, UndefT, DefaultT, NumericT, BinaryT, TimestampT, TimespanT).