| UnableToParseModule | Language.PureScript.Bundle |
| UnacceptableVersion | Language.PureScript.Publish.ErrorsWarnings |
| uname | Language.PureScript.Parser.Lexer, Language.PureScript.Parser, Language.PureScript |
| uname' | Language.PureScript.Parser.Lexer, Language.PureScript.Parser, Language.PureScript |
| UnaryMinus | Language.PureScript.AST.Declarations, Language.PureScript.AST, Language.PureScript |
| UnaryOperator | Language.PureScript.CodeGen.JS.AST, Language.PureScript.CodeGen.JS, Language.PureScript.CodeGen |
| unCheck | Language.PureScript.TypeChecker.Monad, Language.PureScript.TypeChecker, Language.PureScript |
| UndeclaredDependency | Language.PureScript.Publish.ErrorsWarnings |
| Undefined | Language.PureScript.Environment, Language.PureScript |
| undefined | Language.PureScript.Constants |
| UndefinedTypeVariable | Language.PureScript.Errors, Language.PureScript |
| underscore | Language.PureScript.Parser.Lexer, Language.PureScript.Parser, Language.PureScript |
| Unifiable | Control.Monad.Unify |
| UnificationError | Control.Monad.Unify |
| unifiesWith | Language.PureScript.TypeChecker.Unify |
| unifyCurrentSubstitution | Control.Monad.Unify |
| unifyNextVar | Control.Monad.Unify |
| unifyRows | Language.PureScript.TypeChecker.Unify |
| UnifyState | |
| 1 (Type/Class) | Control.Monad.Unify |
| 2 (Data Constructor) | Control.Monad.Unify |
| UnifyT | |
| 1 (Type/Class) | Control.Monad.Unify |
| 2 (Data Constructor) | Control.Monad.Unify |
| unifyTypes | Language.PureScript.TypeChecker.Unify |
| unit | Language.PureScript.Constants |
| Unknown | Control.Monad.Unify |
| unknown | Control.Monad.Unify |
| UnknownDataConstructor | Language.PureScript.Errors, Language.PureScript |
| UnknownMap | Language.PureScript.Errors, Language.PureScript |
| UnknownModule | Language.PureScript.Errors, Language.PureScript |
| unknowns | Control.Monad.Unify |
| UnknownType | Language.PureScript.Errors, Language.PureScript |
| UnknownTypeClass | Language.PureScript.Errors, Language.PureScript |
| UnknownTypeConstructor | Language.PureScript.Errors, Language.PureScript |
| UnknownValue | Language.PureScript.Errors, Language.PureScript |
| unMake | Language.PureScript.Make, Language.PureScript |
| UnnecessaryFFIModule | Language.PureScript.Errors, Language.PureScript |
| unsafeIndex | Language.PureScript.Constants |
| UnspecifiedSkolemScope | Language.PureScript.Errors, Language.PureScript |
| unSupplyT | Control.Monad.Supply, Language.PureScript |
| UnsupportedExport | Language.PureScript.Bundle |
| UnsupportedModulePath | Language.PureScript.Bundle |
| unThunk | Language.PureScript.CodeGen.JS.Optimizer.Inliner |
| untilE | Language.PureScript.Constants |
| unUnify | Control.Monad.Unify |
| unwrapErrorMessage | Language.PureScript.Errors, Language.PureScript |
| UploadedPackage | Language.PureScript.Docs.Types, Language.PureScript.Docs |
| usedTypeVariables | Language.PureScript.Types, Language.PureScript |
| UserError | |
| 1 (Type/Class) | Language.PureScript.Publish.ErrorsWarnings |
| 2 (Data Constructor) | Language.PureScript.Publish.ErrorsWarnings |