README.html

<h1>Extensible Haskell front-end for the Programatica project</h1>

<h2>What is in this directory (base/TI)</h2>

This directory contains a type checker for the base
language (i.e., more or less Haskell 98). It is structured to allow large
parts to be reusable in extended versions of the language.
<p>
At present,
the type inference monad is fixed, and the AST for inferred types is fixed,
but it might be possible to factor out these aspects too.

<p>
Although various details differ, this type checker is influenced by

<ul>
<li>Mark Jones'
    <a href="http://www.cse.ogi.edu/~mpj/thih/"><cite>Typing Haskell in
    Haskell</cite></a> (general guidance, some naming conventions, the class
    <code>Types</code> and operations on substitutions, ...),
<li>one of Johan Nordlander's type checkers for
    <a href="http://www.cs.chalmers.se/~nordland/ohaskell/">O'Haskell</a>
    (that avoids both threading an accumulating substitution and
    applying substitutions to the environment),
<li>and also somewhat by the type checker in
    <a href="http://www.cs.chalmers.se/~augustss/hbc/hbc.html">HBC</a>.
   (HBC serves as a proof that you don't need to resort to imperative
   unification to implement efficient type inference, nor do you need
   to sweep things under the carpet with a monad to make a purely
   functional type checker readable.)
</ul>

<h3>Modules for the basic type inference machinery</h3>

<ul>
<li>TiMonad (NewTiMonad or OrigTiMonad),
TiClasses,
TiConstraints,
TiEnv,
TiFresh,
TiKinds,
TiSolve,
TiTypes,
TiUtil,
TI,
TiPretty,
TiNames,
Unification.

</ul>


<h3>Instances and context reduction</h3>

<ul>
<li>
TiBySuper,
TiContextReduction,
TiDefault,
TiDerivedInstances,
TiInstanceDB.
</ul>


<h3>Type inference for the base language structure</h3>
These should be reusable in extended versions of the language.

<ul>
<li>Declarations: TiD, TiClassInst, TiDkc,
<li>Expressions, patterns, etc: TiE, TiFields, TiLit,TiP, TiRhs,
<li>Kinds inference for type expressions: TiT,
<li>Modules: TiModule,
<li>Collects everything: TiBaseStruct.

</ul>

<h3>Knot-tying definitions for the base language</h3>

<ul>
<li>TiBase, TiDecorate, NameMapsDecorate
</ul>

<h3>Type inference for sequences of declarations</h3>
<ul>
<li>TiDs.
</ul>

<h3>Interfaces to other pieces of reusable code</h3>

<ul>
<li>TiSCC, TiDefinedNames, TiFreeNames.
</ul>

<h3>Other modules</h3>
<ul>
<li>
TiPrelude, TiHsName
</ul>