diff options
| -rw-r--r-- | ghc/docs/comm/index.html | 4 | ||||
| -rw-r--r-- | ghc/docs/comm/the-beast/basicTypes.html | 82 |
2 files changed, 81 insertions, 5 deletions
diff --git a/ghc/docs/comm/index.html b/ghc/docs/comm/index.html index 9b4d45cd7a..ab038e7cb6 100644 --- a/ghc/docs/comm/index.html +++ b/ghc/docs/comm/index.html @@ -6,7 +6,7 @@ </head> <body BGCOLOR="FFFFFF"> - <h1>The Glasgow Haskell Compiler (GHC) Commentary [v0.6]</h1> + <h1>The Glasgow Haskell Compiler (GHC) Commentary [v0.7]</h1> <p> <!-- Contributors: Whoever makes substantial additions or changes to the document, please add your name and keep the order alphabetic. Moreover, @@ -80,7 +80,7 @@ <p><small> <!-- hhmts start --> -Last modified: Mon Nov 26 19:23:12 EST 2001 +Last modified: Tue Jan 8 18:23:25 EST 2002 <!-- hhmts end --> </small> </body> diff --git a/ghc/docs/comm/the-beast/basicTypes.html b/ghc/docs/comm/the-beast/basicTypes.html index 2295db5621..5c102cf9f2 100644 --- a/ghc/docs/comm/the-beast/basicTypes.html +++ b/ghc/docs/comm/the-beast/basicTypes.html @@ -12,7 +12,11 @@ href="http://cvs.haskell.org/cgi-bin/cvsweb.cgi/fptools/ghc/compiler/basicTypes/"><code>fptools/ghc/compiler/basicTypes/</code></a> contains modules that define some of the essential types definition for the compiler - such as, identifiers, variables, modules, and unique - names. + names. Some of those are discussed in the following. Some more + detailed information on <code>Var</code>s, <code>Id</code>s, and + <code>TyVar</code>s is provided <a href="vars.html">elsewhere.</a> + + <h2>Elementary Types</h2> <h4><code>Id</code>s</h4> <p> @@ -44,9 +48,81 @@ (<code>IAmALoopBreaker</code>). </dl> - <p><small> + <h2>Sets, Finite Maps, and Environments</h2> + <p> + Sets of variables, or more generally names, which are needed throughout + the compiler, are provided by the modules <a + href="http://cvs.haskell.org/cgi-bin/cvsweb.cgi/fptools/ghc/compiler/basicTypes/VarSet.lhs"><code>VarSet.lhs</code></a> + and <a + href="http://cvs.haskell.org/cgi-bin/cvsweb.cgi/fptools/ghc/compiler/basicTypes/NameSet.lhs"><code>NameSet.lhs</code></a>, + respectively. Moreover, frequently maps from variables (or names) to + other data is needed. For example, a substitution is represented by a + finite map from variable names to expressions. Jobs like this are + solved by means of variable and name environments implemented by the + modules <a + href="http://cvs.haskell.org/cgi-bin/cvsweb.cgi/fptools/ghc/compiler/basicTypes/VarEnv.lhs"><code>VarEnv.lhs</code></a> + and <a + href="http://cvs.haskell.org/cgi-bin/cvsweb.cgi/fptools/ghc/compiler/basicTypes/NameEnv.lhs"><code>NameEnv.lhs</code></a>. + + <h4>The Module <code>VarSet</code></h4> + <p> + The Module <code>VarSet</code> provides the types <code>VarSet</code>, + <code>IdSet</code>, and <code>TyVarSet</code>, which are synonyms in the + current implementation, as <code>Var</code>, <code>Id</code>, and + <code>TyVar</code> are synonyms. The module provides all the operations + that one would expect including the creating of sets from individual + variables and lists of variables, union and intersection operations, + element checks, deletion, filter, fold, and map functions. + <p> + The implementation is based on <a + href="http://cvs.haskell.org/cgi-bin/cvsweb.cgi/fptools/ghc/compiler/utils/UniqSet.lhs"><code>UniqSet</code></a>s, + which in turn are simply <a href="http://cvs.haskell.org/cgi-bin/cvsweb.cgi/fptools/ghc/compiler/utils/UniqFM.lhs"><code>UniqFM</code></a>s + (i.e., finite maps with uniques as keys) that map each unique to the + variable that it represents. + + <h4>The Module <code>NameSet</code></h4> + <p> + The Module <code>NameSet</code> provides the same functionality as + <code>VarSet</code> only for <a + href="http://cvs.haskell.org/cgi-bin/cvsweb.cgi/fptools/ghc/compiler/basicTypes/Name.lhs"><code>Name<code></a>s. + As for the difference between <code>Name</code>s and <code>Var</code>s, + a <code>Var</code> is built from a <code>Name</code> plus additional + information (mostly importantly type information). + + <h4>The Module <code>VarEnv</code></h4> + <p> + The module <code>VarEnv</code> provides the types <code>VarEnv</code>, + <code>IdEnv</code>, and <code>TyVarEnv</code>, which are again + synonyms. The provided base functionality is similar to + <code>VarSet</code> with the main difference that a type <code>VarEnv + T</code> associates a value of type <code>T</code> with each variable in + the environment, thus effectively implementing a finite map from + variables to values of type <code>T</code>. + <p> + The implementation of <code>VarEnv</code> is also by <a + href="http://cvs.haskell.org/cgi-bin/cvsweb.cgi/fptools/ghc/compiler/utils/UniqFM.lhs"><code>UniqFM</code></a>, + which entails the slightly surprising implication that it is + <em>not</em> possible to retrieve the domain of a variable environment. + In other words, there is no function corresponding to + <code>VarSet.varSetElems :: VarSet -> [Var]</code> in + <code>VarEnv</code>. This is because the <code>UniqFM</code> used to + implement <code>VarEnv</code> stores only the unique corresponding to a + variable in the environment, but not the entire variable (and there is + no mapping from uniques to variables). + <p> + In addition to plain variable environments, the module also contains + special substitution environments - the type <code>SubstEnv</code> - + that associates variables with a special purpose type + <code>SubstResult</code>. + + <h4>The Module <code>NameEnv</code></h4> + <p> + The type <code>NameEnv.NameEnv</code> is like <code>VarEnv</code> only + for <code>Name</code>s. + + <p><hr><small> <!-- hhmts start --> -Last modified: Wed Aug 8 19:23:01 EST 2001 +Last modified: Tue Jan 8 18:29:52 EST 2002 <!-- hhmts end --> </small> </body> |