# The thih package

Haskell benefits from a sophisticated type system, but implementors,
programmers, and researchers suffer because it has no formal description.
To remedy this shortcoming, we present a Haskell program that implements
a Haskell typechecker, thus providing a mathematically rigorous specification
in a notation that is familiar to Haskell users. We expect this program to fill
a serious gap in current descriptions of Haskell, both as a starting point
for discussions about existing features of the type system, and as a platform
from which to explore new proposals.

This package is derived from the Haskell '98 + Multiparameter Type Classes package of THIH.

[

Skip to ReadMe]

## Properties

## Modules

[Index]

## Downloads

#### Maintainers' corner

For package maintainers and hackage trustees

## Readme for thih-1.0

>----------------------------------------------------------------------------<
Typing Haskell in Haskell: README
Mark P Jones
mpj@cse.ogi.edu
Pacific Software Research Center
Department of Computer Science and Engineering
Oregon Graduate Insitute of Science and Technology
Thanksgiving Day 2000 (November 23, 2000)
This package contains source code for a Haskell typechecker that is
written in Haskell. This is a revised version of the program that was
presented at the 3rd Haskell Workshop in Paris on October 1, 1999.
These files have been tested using the Hugs 98 interpreter, but should
be readily adapted to other Haskell 98 systems. These programs are
distributed as Free Software under the terms in the file "License" that
is included in the distribution of this software, copies of which may
be obtained from: <http://www.cse.ogi.edu/~mpj/thih/>.
Please note that further revisions to this software may already be
planned or in progress.
The following list describes each of the files in the distribution:
Readme
This file
License
The license for distribution and use of this software
A more realistic version of the typchecker, broken in to separate
modules (roughly following the structure of the paper), together
with additional code used for debugging and pretty printing.
Assump.hs
Assumption lists.
Debug.hs
A simple debug function that was used during testing. It is
not actually used in the distributed code.
Id.hs
Identifiers.
Infer.hs
Captures the general form of many type inference judgements.
Kind.hs
Kinds.
Lit.hs
Literals.
Pat.hs
Patterns.
PPrint.hs
A pretty printing library, which builds on the pretty printing
library included in the standard Hugs distribution.
Pred.hs
Predicates and qualified types.
Scheme.hs
Type schemes.
Subst.hs
Substitutions.
Testbed.hs
A simple test bed, providing functions to type check a collection
of binding groups, and output or save the results.
TIMain.hs
Type inference for expressions, binding groups, etc.
TIMonad.hs
The definition of a simple monad for type inference.
TIProg.hs
Type inference for top-level programs.
Type.hs
Types.
Unify.hs
Unification.
The remaining files provide test data of one form or another, based
where necessary on Haskell coded included in the Hugs distribution:
Static.hs
Definitions for use in describing the static (types + classes)
component of a module.
HaskellPrims.hs
Typing assumptions for Hugs primitives that are used in the Prelude.
StaticPrelude.hs
Describes the static environment (types + classes) for the Prelude.
SourcePrelude.hs
An encoding of the standard Prelude library as Haskell data that
can be fed into the type checker.
HaskellPrelude.hs
A set of typing assumptions for Prelude functions, generated
automatically by running the savePrelude function in SourcePrelude.hs.
StaticMaybe.hs
Describes the static environment (types + classes) for the Maybe library.
SourceMaybe.hs
An encoding of the standard Maybe library as a Haskell data structure.
HaskellMaybe.hs
Typing assumptions for the Maybe library, generated by running the
saveMaybe function in SourceMaybe.hs.
StaticList.hs
Describes the static environment (types + classes) for the List library.
SourceList.hs
An encoding of the standard List library as a Haskell data structure.
HaskellList.hs
Typing assumptions for the List library, generated by running the
saveList function in SourceList.hs.
StaticMonad.hs
Describes the static environment (types + classes) for the Monad library.
SourceMonad.hs
An encoding of the standard Monad library as a Haskell data structure.
HaskellMonad.hs
Typing assumptions for the Monad library, generated by running the
saveMonad function in SourceMonad.hs.
StaticThih.hs
Describes the static environment (types + classes) for the typechecker.
SourceThih.hs
An encoding of the typechecker as a Haskell data structure.
HaskellThih.hs
Typing assumptions for the typechecker, generated by running the
saveThih function in SourceMaybe.hs.
StaticTest.hs
Describes the static environment (types + classes) for the test program.
SourceTest.hs
An encoding of misc Haskell functions as a Haskell data structure.
HaskellTest.hs
Typing assumptions generated by running the saveTest function in
SourceTest.hs.
Simple example of use:
$ ghci Main.hs
Main> main
... wait a while for the inferred list of typings to be displayed ...
------------------------------------------------------------------------------