5 files changed, 54 insertions(+), 45 deletions(-)

M compiler.rb
M compiler/lib/scheme/base.rb
M compiler/lib/scheme/process_context.rb
M compiler/lib/scheme/write.rb
M compiler/libraries.rb

@@ 69,6 69,12 @@ class Compiler
     )
   end
 
+  def compile_sexps_use_last(sexps, options:)
+    return [] if sexps.empty?
+    sexps[0..-2].map { |s| compile_sexp_discard(s, options) } +
+      [compile_sexp_use(sexps.last, options)]
+  end
+
   def optimize(instructions)
     Optimizer.new(instructions).optimize
   end


@@ 80,6 86,14 @@ class Compiler
     dispatch(sexp, options)
   end
 
+  def compile_sexp_use(sexp, options = { locals: {} })
+    compile_sexp(sexp, options.merge(use: true))
+  end
+
+  def compile_sexp_discard(sexp, options = { locals: {} })
+    compile_sexp(sexp, options.merge(use: false))
+  end
+
   def dispatch(sexp, options)
     (name, *args) = sexp
     if options[:quote] || options[:quasiquote]


@@ 121,7 135,7 @@ class Compiler
     end
   end
 
-  def compile_literal(literal, options = { use: false, locals: {} })
+  def compile_literal(literal, options = { locals: {} })
     case literal.to_s.strip
     when /\A-?[0-9]+\z/
       compile_number(literal, options)


@@ 221,9 235,9 @@ class Compiler
   end
 
   def call((lambda, *args), options)
-    function = compile_sexp(lambda, options.merge(use: true))
+    function = compile_sexp_use(lambda, options)
     [
-      args.map { |arg| compile_sexp(arg, options.merge(use: true)) },
+      args.map { |arg| compile_sexp_use(arg, options) },
       args.any? ? [VM::PUSH_NUM, args.size, VM::SET_ARGS] : nil,
       function,
       VM::CALL


@@ 232,8 246,8 @@ class Compiler
 
   def compile_pair((car, _, cdr), options)
     [
-      compile_sexp(car, options.merge(use: true)),
-      compile_sexp(cdr, options.merge(use: true)),
+      compile_sexp_use(car, options),
+      compile_sexp_use(cdr, options),
       VM::CONS,
       pop_maybe(options)
     ]

@@ 4,7 4,7 @@ class Compiler
       module Base
         def base_append(args, options)
           [
-            args.map { |arg| compile_sexp(arg, options.merge(use: true)) },
+            args.map { |arg| compile_sexp_use(arg, options) },
             VM::PUSH_NUM, args.size,
             VM::APPEND,
             pop_maybe(options)


@@ 14,10 14,10 @@ class Compiler
         def base_apply((lambda, *args), options)
           raise 'apply expects at least 2 arguments' if args.empty?
           [
-            args.map { |arg| compile_sexp(arg, options.merge(use: true)) },
+            args.map { |arg| compile_sexp_use(arg, options) },
             VM::PUSH_NUM, args.size,
             VM::SET_ARGS,
-            compile_sexp(lambda, options.merge(use: true)),
+            compile_sexp_use(lambda, options),
             VM::APPLY
           ]
         end


@@ 33,7 33,7 @@ class Compiler
           else
             options[:locals][name] = true
             [
-              compile_sexp(body.first, options.merge(use: true)),
+              compile_sexp_use(body.first, options),
               VM::DEFINE_VAR, name
             ]
           end


@@ 51,14 51,14 @@ class Compiler
 
         def base_call_cc((fn), options)
           [
-            compile_sexp(fn, options.merge(use: true)),
+            compile_sexp_use(fn, options),
             VM::CALL_WITH_CC
           ]
         end
 
         def base_car((arg, *_rest), options)
           [
-            compile_sexp(arg, options.merge(use: true)),
+            compile_sexp_use(arg, options),
             VM::CAR,
             pop_maybe(options)
           ]


@@ 67,7 67,7 @@ class Compiler
         def base_cons(args, options)
           raise 'cons expects exactly 2 arguments' if args.size != 2
           [
-            args.map { |arg| compile_sexp(arg, options.merge(use: true)) },
+            args.map { |arg| compile_sexp_use(arg, options) },
             VM::CONS,
             pop_maybe(options)
           ]


@@ 75,18 75,18 @@ class Compiler
 
         def base_cdr((arg, *_rest), options)
           [
-            compile_sexp(arg, options.merge(use: true)),
+            compile_sexp_use(arg, options),
             VM::CDR,
             pop_maybe(options)
           ]
         end
 
         def base_if((condition, true_body, false_body), options)
-          true_instr  = compile_sexp(true_body, options.merge(use: true)).flatten.compact
-          false_instr = compile_sexp(false_body, options.merge(use: true)).flatten.compact
+          true_instr  = compile_sexp_use(true_body, options).flatten.compact
+          false_instr = compile_sexp_use(false_body, options).flatten.compact
           false_instr = [VM::PUSH_UNDEF] if false_instr.empty?
           [
-            compile_sexp(condition, options.merge(use: true)),
+            compile_sexp_use(condition, options),
             VM::JUMP_IF_FALSE, true_instr.size + 3,
             true_instr,
             VM::JUMP, false_instr.size + 1,


@@ 134,10 134,8 @@ class Compiler
         end
 
         def compile_lambda_body(body, locals, options)
-          body_opts = options.merge(use: true, locals: locals, syntax: options[:syntax].dup)
-          body.each_with_index.map do |sexp, index|
-            compile_sexp(sexp, body_opts.merge(use: index == body.size - 1))
-          end
+          body_opts = options.merge(locals: locals, syntax: options[:syntax].dup)
+          compile_sexps_use_last(body, options: body_opts)
         end
 
         def base_let_syntax((bindings, *body), options)


@@ 163,14 161,12 @@ class Compiler
               transformer: transformer
             }
           end
-          body.each_with_index.map do |sexp, index|
-            compile_sexp(sexp, body_opts.merge(use: index == body.size - 1))
-          end
+          compile_sexps_use_last(body, options: body_opts)
         end
 
         def base_list(args, options)
           members = args.flat_map do |arg|
-            expr = compile_sexp(arg, options.merge(use: true))
+            expr = compile_sexp_use(arg, options)
             if expr.first == 'splice'
               expr.last
             else


@@ 187,7 183,7 @@ class Compiler
 
         def base_list_to_string((list, *_rest), options)
           [
-            compile_sexp(list, options.merge(use: true)),
+            compile_sexp_use(list, options),
             VM::TO_STR,
             pop_maybe(options)
           ]


@@ 195,7 191,7 @@ class Compiler
 
         def base_null?((arg, *_rest), options)
           [
-            compile_sexp(arg, options.merge(use: true)),
+            compile_sexp_use(arg, options),
             VM::CMP_NULL,
             pop_maybe(options)
           ]


@@ 219,15 215,15 @@ class Compiler
 
         def base_set_car!((pair, new_car), options)
           [
-            compile_sexp(pair, options.merge(use: true)),
-            compile_sexp(new_car, options.merge(use: true)),
+            compile_sexp_use(pair, options),
+            compile_sexp_use(new_car, options),
             VM::SET_CAR
           ]
         end
 
         def base_set!((name, val), options)
           [
-            compile_sexp(val, options.merge(use: true)),
+            compile_sexp_use(val, options),
             VM::SET_VAR,
             name
           ]


@@ 235,15 231,15 @@ class Compiler
 
         def base_set_cdr!((pair, new_cdr), options)
           [
-            compile_sexp(pair, options.merge(use: true)),
-            compile_sexp(new_cdr, options.merge(use: true)),
+            compile_sexp_use(pair, options),
+            compile_sexp_use(new_cdr, options),
             VM::SET_CDR
           ]
         end
 
         def base_string(chars, options)
           [
-            chars.map { |char| compile_sexp(char, options.merge(use: true)) },
+            chars.map { |char| compile_sexp_use(char, options) },
             VM::PUSH_NUM, chars.size,
             VM::PUSH_LIST,
             VM::TO_STR,


@@ 253,7 249,7 @@ class Compiler
 
         def base_string_length((string, *_rest), options)
           [
-            compile_sexp(string, options.merge(use: true)),
+            compile_sexp_use(string, options),
             VM::STR_LEN,
             pop_maybe(options)
           ]


@@ 261,8 257,8 @@ class Compiler
 
         def base_string_ref((string, index), options)
           [
-            compile_sexp(string, options.merge(use: true)),
-            compile_sexp(index, options.merge(use: true)),
+            compile_sexp_use(string, options),
+            compile_sexp_use(index, options),
             VM::STR_REF,
             pop_maybe(options)
           ]


@@ 270,14 266,14 @@ class Compiler
 
         def base_char_to_integer((char), options)
           [
-            compile_sexp(char, options.merge(use: true)),
+            compile_sexp_use(char, options),
             VM::RAW
           ]
         end
 
         def base_integer_to_char((int), options)
           [
-            compile_sexp(int, options.merge(use: true)),
+            compile_sexp_use(int, options),
             VM::TO_CHAR
           ]
         end


@@ 291,7 287,7 @@ class Compiler
         }.each do |name, type|
           define_method "base_#{name}" do |(arg, *_rest), options|
             [
-              compile_sexp(arg, options.merge(use: true)),
+              compile_sexp_use(arg, options),
               VM::TYPE,
               VM::PUSH_NUM, VM::TYPES.index(type),
               VM::CMP_EQ,


@@ 318,7 314,7 @@ class Compiler
         end
 
         def arith(instruction, args, options)
-          args = args.map { |arg| compile_sexp(arg, options.merge(use: true)) }
+          args = args.map { |arg| compile_sexp_use(arg, options) }
           first_two = args.shift(2)
           rest = args.zip([instruction] * args.size)
           [


@@ 343,7 339,7 @@ class Compiler
         def compare(instruction, args, options)
           raise "wrong number of arguments (expected 2, got #{args.size})" if args.size != 2
           [
-            args.map { |arg| compile_sexp(arg, options.merge(use: true)) },
+            args.map { |arg| compile_sexp_use(arg, options) },
             instruction,
             pop_maybe(options)
           ]

@@ 4,7 4,7 @@ class Compiler
       module ProcessContext
         def process_exit((arg, *_rest), options)
           [
-            arg && compile_sexp(arg, options.merge(use: true)),
+            arg && compile_sexp_use(arg, options),
             VM::HALT
           ]
         end

@@ 4,7 4,7 @@ class Compiler
       module Write
         def write(args, options)
           [
-            args.map { |arg| compile_sexp(arg, options.merge(use: true)) },
+            args.map { |arg| compile_sexp_use(arg, options) },
             VM::INT, VM::INT_WRITE
           ]
         end

@@ 106,8 106,7 @@ class Compiler
       }
       imports = []
       begins = []
-      # TODO: probably shouldn't dup locals either
-      lib_opts = options.merge(use: true, locals: options[:locals].dup, syntax: exports[:syntax], lib: name_as_string)
+      lib_opts = options.merge(syntax: exports[:syntax], lib: name_as_string)
       declarations.each do |(type, *args)|
         case type
         when 'export'


@@ 121,7 120,7 @@ class Compiler
       [
         VM::SET_LIB, name_as_string,
         imports,
-        begins.map { |s| compile_sexp(s, lib_opts) },
+        begins.map { |s| compile_sexp_discard(s, lib_opts) },
         VM::ENDL
       ]
     end