Work on documentation

docs/about_forth.md

@@ -1,16 +1,16 @@
 # About Forth
 
-Forth is a stack-based programming language created by Charles H. Moore in the early 1970s. It was designed for simplicity, directness, and interactive exploration. Forth has been used for many years to do scientific work and program embedded systems: controlling telescopes, running on devices used in space missions, etc. Forth quickly evolved into multiple implementations. None of them really reached an incredible popularity. Nonetheless, the ideas behind Forth continue to garner the interest of many different people in very different (often unrelated) fields. Nowadays, Forth languages are sometimes used by hackers and artists for their peculiarities. A Forth implementation is often simple, direct and beautiful. Forth is an elegant and minimal language to learn. It is easy to understand, to extend and to apply to a specific task. The Forth we use in Cagire is specialized in making live music.
+Forth is a _stack-based_ programming language created by Charles H. Moore in the early 1970s. It was designed with simplicity, directness, and interactive exploration in mind. Forth has been used for many years to do scientific work and program embedded systems: it was used to control telescopes and was running on some devices used in space missions among other things. Forth quickly evolved into multiple implementations targetting various computer architectures. None of them really took off and became popular. Nonetheless, the ideas behind Forth continue to garner the interest of many different people in very different (often unrelated) fields. Nowadays, Forth languages are used by hackers and artists for their peculiarity. Forth is simple, direct and beautiful to implement. Forth is an elegant and minimal language to learn. It is easy to understand, to extend and to apply to a specific task. The Forth we use in Cagire is specialized in making live music. We think of it as a DSL: a _Domain Specific Language_. 
 
 ## Why Forth?
 
-Most programming languages nowadays use a complex syntax made of `variables`, `expressions` and `statements` like `x = 3 + 4`. Forth works differently. It is way more simple than that, has almost no syntax, and performs computations in a quite unique way. You push values onto a `stack` and apply `words` that transform them:
+Most programming languages nowadays use a complex syntax made of `variables`, `expressions` and `statements` like `x = 3 + 4`. Forth works differently. It is way more simple than that, has almost no syntax and performs computations in a quite unique way. You push values onto a `stack` and apply `words` that transform them:
 
 ```forth
 3 4 +
 ```
 
-This program leaves the number `7` on the stack. There are no variables, no parentheses, no syntax to remember. You just end up with words and numbers separated by spaces. For live coding music, this directness is quite exciting. All you do is thinking in terms of transformations and adding things to the stack: take a note, shift it up, add reverb, play it.
+This program leaves the number `7` on the stack. There are no variables, no parentheses, no syntax to remember. You just end up with words and numbers separated by spaces. For live coding music, this directness is quite exciting. All you do is think in terms of transformations and add things to the stack: take a note, shift it up, add reverb, play it.
 
 ## The Stack
 
@@ -40,7 +40,7 @@ Words compose naturally on the stack. To double a number:
 3 dup +   ( 3 3 +)
 ```
 
-There are a lot of words in a Forth, and thus, Cagire has a `Dictionary` embedded directly into the application. You can also create your own words. They will work just like the already existing words. There are good reasons to create new words on-the-fly:
+There are a lot of words in a Forth and thus, Cagire has a `Dictionary` embedded directly into the application. You can also create your own words. They will work just like the already existing words. There are good reasons to create new words on-the-fly:
 
 - To make synth definitions.
 - To abstract _some piece of code_ that you use frequently.
@@ -69,11 +69,9 @@ For example, `+` has the signature `( a b -- sum )`. It takes two values and lea
 
 ## The Command Register
 
-Traditional Forth programs print text to a terminal. Cagire's Forth builds sound commands instead. This happens through an invisible accumulator called the command register.
-
-The command register has two parts:
-- A **sound name** (what instrument to play)
-- A list of **parameters** (how to play it)
+Traditional Forth programs print text to a terminal. Cagire's Forth builds sound commands instead. This happens through an invisible accumulator called the command register. The command register has two parts:
+- a **sound name** (what instrument to play)
+- a list of **parameters** (how to play it)
 
 Three types of words interact with it:
 
@@ -102,7 +100,7 @@ Each line adds something to the register. The final `.` triggers the sound. You
 "sine" s c4 note 0.5 gain 0.3 decay 0.4 verb .
 ```
 
-The order of parameters does not matter. You can even emit multiple times in a single step: If you need to discard the register without emitting, use `clear`:
+The order of parameters does not matter. You can even emit multiple times in a single step. If you need to discard the register without emitting, use `clear`:
 
 ```forth
 "kick" s 0.5 gain clear    ;; nothing plays, register is emptied
@@ -110,3 +108,8 @@ The order of parameters does not matter. You can even emit multiple times in a s
 ```
 
 This is useful when conditionals might cancel a sound before it emits.
+
+## More details
+
+- Each step has its own stack and independant runtime.
+- Word definitions and variable definitions are shared by all steps.