From ab6e6fae4e8935fca5fb33bd8645fe9cece18bb9 Mon Sep 17 00:00:00 2001
From: Joel Martin <github@martintribe.org>
Date: Sat, 7 Feb 2015 22:07:16 -0600
Subject: matlab: step3

---
 matlab/Env.m        | 36 ++++++++++++++++++++++++
 matlab/step2_eval.m | 10 ++++---
 matlab/step3_env.m  | 80 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 122 insertions(+), 4 deletions(-)
 create mode 100644 matlab/Env.m
 create mode 100644 matlab/step3_env.m

diff --git a/matlab/Env.m b/matlab/Env.m
new file mode 100644
index 0000000..1d080a3
--- /dev/null
+++ b/matlab/Env.m
@@ -0,0 +1,36 @@
+classdef Env < handle
+    properties
+        data
+        outer
+    end
+    methods
+        function env = Env(outer)
+            env.data = containers.Map();
+            env.outer = outer;
+        end
+        function ret = set(env, k, v)
+            env.data(k.name) = v;
+            ret = v;
+        end
+        function ret = find(env, k)
+            if env.data.isKey(k.name)
+                ret = env;
+            else
+                if ~islogical(env.outer) 
+                    ret = env.outer.find(k);
+                else
+                    ret = false;
+                end
+            end
+        end
+        function ret = get(env, k)
+            fenv = env.find(k);
+            if ~islogical(fenv)
+                ret = fenv.data(k.name);
+            else
+                throw(MException('ENV:notfound', ...
+                                 strcat('''', k.name, ''' not found')));
+            end
+        end
+    end
+end
diff --git a/matlab/step2_eval.m b/matlab/step2_eval.m
index 418bb84..4ce13fb 100644
--- a/matlab/step2_eval.m
+++ b/matlab/step2_eval.m
@@ -1,4 +1,4 @@
-function step1_read_print(varargin), main(varargin), end
+function step2_eval(varargin), main(varargin), end
 
 % read
 function ret = READ(str)
@@ -44,9 +44,11 @@ function ret = rep(str, env)
 end
 
 function main(args)
-    repl_env = containers.Map( ...
-        {'+', '-', '*', '/'}, ...
-        {@(a,b) a+b, @(a,b) a-b, @(a,b) a*b, @(a,b) floor(a/b)});
+    repl_env = containers.Map();
+    repl_env('+') = @(a,b) a+b;
+    repl_env('-') = @(a,b) a-b;
+    repl_env('*') = @(a,b) a*b;
+    repl_env('/') = @(a,b) floor(a/b);
 
     %cleanObj = onCleanup(@() disp('*** here1 ***'));
     while (true)
diff --git a/matlab/step3_env.m b/matlab/step3_env.m
new file mode 100644
index 0000000..6ac6426
--- /dev/null
+++ b/matlab/step3_env.m
@@ -0,0 +1,80 @@
+function step3_env(varargin), main(varargin), end
+
+% read
+function ret = READ(str)
+    ret = reader.read_str(str);
+end
+
+% eval
+function ret = eval_ast(ast, env)
+    switch class(ast)
+    case 'types.Symbol'
+        ret = env.get(ast);
+    case 'cell'
+        ret = {};
+        for i=1:length(ast)
+            ret{end+1} = EVAL(ast{i}, env);
+        end
+    otherwise
+        ret = ast;
+    end
+end
+
+function ret = EVAL(ast, env)
+    if ~iscell(ast),
+        ret = eval_ast(ast, env);
+        return;
+    end
+
+    % apply
+    if isa(ast{1},'types.Symbol')
+        a1sym = ast{1}.name;
+    else
+        a1sym = '_@$fn$@_';
+    end
+    switch (a1sym)
+    case 'def!'
+        ret = env.set(ast{2}, EVAL(ast{3}, env));
+    case 'let*'
+        let_env = Env(env);
+        for i=1:2:length(ast{2})
+            let_env.set(ast{2}{i}, EVAL(ast{2}{i+1}, let_env));
+        end
+        ret = EVAL(ast{3}, let_env);
+    otherwise
+        el = eval_ast(ast, env);
+        f = el{1};
+        args = el(2:end);
+        ret = f(args{:});
+    end
+end
+
+% print
+function ret = PRINT(ast)
+    ret = printer.pr_str(ast, true);
+end
+
+% REPL
+function ret = rep(str, env)
+    ret = PRINT(EVAL(READ(str), env));
+end
+
+function main(args)
+    repl_env = Env(false);
+    repl_env.set(types.Symbol('+'), @(a,b) a+b);
+    repl_env.set(types.Symbol('-'), @(a,b) a-b);
+    repl_env.set(types.Symbol('*'), @(a,b) a*b);
+    repl_env.set(types.Symbol('/'), @(a,b) floor(a/b));
+
+    %cleanObj = onCleanup(@() disp('*** here1 ***'));
+    while (true)
+        line = input('user> ', 's');
+        if strcmp(strtrim(line),''), continue, end
+        try
+            fprintf('%s\n', rep(line, repl_env));
+        catch err
+            fprintf('Error: %s\n', err.message);
+            fprintf('%s\n', getReport(err, 'extended'));
+        end
+    end
+end
-- 
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