From e5d9aee00b0c775df1d8e2d8819aeb80dffa73c2 Mon Sep 17 00:00:00 2001 From: Nadrieril Date: Fri, 1 Mar 2019 17:28:19 +0100 Subject: Split abnf_to_pest and dhall into their own crates --- dhall/src/errors/MustMergeARecord.txt | 43 +++++++++++++++++++++++++++++++++++ 1 file changed, 43 insertions(+) create mode 100644 dhall/src/errors/MustMergeARecord.txt (limited to 'dhall/src/errors/MustMergeARecord.txt') diff --git a/dhall/src/errors/MustMergeARecord.txt b/dhall/src/errors/MustMergeARecord.txt new file mode 100644 index 0000000..79094bd --- /dev/null +++ b/dhall/src/errors/MustMergeARecord.txt @@ -0,0 +1,43 @@ +Explanation: You can ❰merge❱ the alternatives of a union using a record with one +handler per alternative, like this: + + + ┌─────────────────────────────────────────────────────────────────────┐ + │ let union = < Left = +2 | Right : Bool > │ + │ in let handlers = { Left = Natural/even, Right = λ(x : Bool) → x } │ + │ in merge handlers union : Bool │ + └─────────────────────────────────────────────────────────────────────┘ + + +... but the first argument to ❰merge❱ must be a record and not some other type. + +For example, the following expression is $_NOT valid: + + + ┌─────────────────────────────────────────┐ + │ let handler = λ(x : Bool) → x │ + │ in merge handler < Foo = True > : True │ + └─────────────────────────────────────────┘ + ⇧ + Invalid: ❰handler❱ isn't a record + + +You provided the following handler: + +↳ $txt0 + +... which is not a record, but is actually a value of type: + +↳ $txt1 + +Some common reasons why you might get this error: + +● You accidentally provide an empty record type instead of an empty record when + you ❰merge❱ an empty union: + + + ┌──────────────────────────────────────────┐ + │ λ(x : <>) → λ(a : Type) → merge {} x : a │ + └──────────────────────────────────────────┘ + ⇧ + This should be ❰{=}❱ instead -- cgit v1.2.3