Dhall.Csv

This library exports two functions: dhallToCsv and codeToValue. The former converts a Dhall expression (with imports resolved already) into a sequence of CSV NamedRecords (from the cassava library) while the latter converts a Text containing Dhall code into a list of CSV NamedRecords.

Not all Dhall expressions can be converted to CSV since CSV is not a programming language. The only things you can convert are Lists of records where each field is one of the following types:

• Bools
• Naturals
• Integers
• Doubles
• Text values
• Optional (of valid field types)
• unions (of empty alternatives or valid record field types)

Dhall Bools translate to either `"true"` or `"false"` in all lowercase letters:

$ dhall-to-csv <<< '[{ exampleBool = True }]'
exampleBool
true
$ dhall-to-csv <<< '[{ exampleBool = False }]'
exampleBool
false

Dhall numbers translate to their string representations:

$ dhall-to-csv <<< '[{ exampleInteger = +2 }]'
exampleInteger
2
$ dhall-to-csv <<< '[{ exampleNatural = 2 }]'
exampleNatural
2
$ dhall-to-csv <<< '[{ exampleDouble = 2.3 }]'
exampleDouble
2.3

Dhall Text translates directly to CSV. Special CSV characters are enclosed by double quotes:

$ dhall-to-csv <<< '[{ exampleText = "ABC" }]'
exampleText
ABC
$ dhall-to-csv <<< '[{ exampleText = "ABC,ABC" }]'
exampleText
"ABC,ABC"

Dhall Optional values translate to the empty string if absent and the unwrapped value otherwise:

$ dhall-to-csv <<< '[{ exampleOptional = None Natural }]'
exampleOptional

$ dhall-to-csv <<< '[{ exampleOptional = Some 1 }]'
exampleOptional
1

Dhall unions translate to the wrapped value or the name of the field (in case it is an empty field):

$ dhall-to-csv <<< "[{ exampleUnion = < Left | Right : Natural>.Left }]"
exampleUnion
Left
$ dhall-to-csv <<< "[{ exampleUnion = < Left | Right : Natural>.Right 2 }]"
exampleUnion
2

Also, all Dhall expressions are normalized before translation to CSV:

$ dhall-to-csv <<< "[{ equality = True == False }]"
equality
false

Documentation

dhallToCsv :: Expr s Void -> Either CompileError (Seq NamedRecord)

Convert a Dhall expression (with resolved imports) to an sequence of CSV NamedRecords.

codeToValue :: Maybe FilePath -> Text -> IO [NamedRecord]

Convert a Text with Dhall code to a list of NamedRecords.

Exceptions

data CompileError

This is the exception type for errors that can arise when converting from Dhall to CSV.

It contains information on the specific cases that might fail to give a better insight.

Instances

Show CompileError

Defined in Dhall.Csv

Methods

showsPrec :: Int -> CompileError -> ShowS

show :: CompileError -> String

showList :: [CompileError] -> ShowS

Exception CompileError

Defined in Dhall.Csv

Methods

toException :: CompileError -> SomeException

fromException :: SomeException -> Maybe CompileError

displayException :: CompileError -> String