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authorNadrieril2019-03-01 17:28:19 +0100
committerNadrieril2019-03-01 17:28:19 +0100
commite5d9aee00b0c775df1d8e2d8819aeb80dffa73c2 (patch)
treee763a24a0d635048232e72e167ca37eafec69369 /dhall/src/errors/IfBranchMustBeTerm.txt
parent8a2b7536902831079eddd7b00291b718f5dd7186 (diff)
Split abnf_to_pest and dhall into their own crates
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+Explanation: Every ❰if❱ expression begins with a predicate which must have type
+❰Bool❱
+
+For example, these are valid ❰if❱ expressions:
+
+
+ ┌──────────────────────────────┐
+ │ if True then "Yes" else "No" │
+ └──────────────────────────────┘
+ ⇧
+ Predicate
+
+
+ ┌─────────────────────────────────────────┐
+ │ λ(x : Bool) → if x then False else True │
+ └─────────────────────────────────────────┘
+ ⇧
+ Predicate
+
+
+... but these are $_NOT valid ❰if❱ expressions:
+
+
+ ┌───────────────────────────┐
+ │ if 0 then "Yes" else "No" │ ❰0❱ does not have type ❰Bool❱
+ └───────────────────────────┘
+
+
+ ┌────────────────────────────┐
+ │ if "" then False else True │ ❰""❱ does not have type ❰Bool❱
+ └────────────────────────────┘
+
+
+Your ❰if❱ expression begins with the following predicate:
+
+↳ $txt0
+
+... that has type:
+
+↳ $txt1
+
+... but the predicate must instead have type ❰Bool❱
+
+Some common reasons why you might get this error:
+
+● You might be used to other programming languages that accept predicates other
+ than ❰Bool❱
+
+ For example, some languages permit ❰0❱ or ❰""❱ as valid predicates and treat
+ them as equivalent to ❰False❱. However, the Dhall language does not permit
+ this