ref: 8f3e065e62d12d0b82a5729afb152fe4670a0174
parent: 9dd33d5098c2784d246ce385e6acb7d1aea58df1
author: Ori Bernstein <ori@eigenstate.org>
date: Wed Aug 8 07:39:20 EDT 2012
More docs.
--- a/doc/lang.txt
+++ b/doc/lang.txt
@@ -1,5 +1,5 @@
The Myrddin Programming Language
- Aug 2012
+ Jul 2012
Ori Bernstein
1. OVERVIEW:
@@ -60,8 +60,77 @@
Literals are a direct representation of a data object within the
source of the program. There are several literals implemented
- within the Myrddin language:
+ within the Myrddin language. These are fully described in sectio
+3. SYNTAX OVERVIEW:
+
+ Myrddin syntax will likely have a familiar-but-strange taste
+ to many people. Many of the concepts and constructions will be
+ similar to those present in C, but different.
+
+ 3.1. Declarations:
+
+ A declaration consists of a declaration class (ie, one
+ of 'const', 'var', or 'generic'), followed by a declaration
+ name, optionally followed by a type and assignment. One thing
+ you may note is that unlike most other languages, there is no
+ special function declaration syntax. Instead, a function is
+ declared like any other value: By assigning its name to a
+ constant or variable.
+
+ const: Declares a constant value, which may not be
+ modified at run time. Constants must have
+ initializers defined.
+ var: Declares a variable value. This value may be
+ assigned to, copied from, and
+ generic: Declares a specializable value. This value
+ has the same restricitions as a const, but
+ taking its address is not defined. The type
+ parameters for a generic must be explicitly
+ named in the declaration in order for their
+ substitution to be allowed.
+
+ In addition, there is one modifier allowed on declarations:
+ 'extern'. Extern declarations are used to declare symbols from
+ another module which cannot be provided via the 'use' mechanism.
+ Typical uses would be to expose a function written in assembly. They
+ can also be used as a workaround for external dependencies.
+
+ Examples:
+
+ Declare a constant with a value 123. The type is not defined,
+ and will be inferred.
+
+ const x = 123
+
+ Declares a variable with no value and no type defined. The
+ value can be assigned later (and must be assigned before use),
+ and the type will be inferred.
+
+ var y
+
+ Declares a generic with type '@a', and assigns it the value
+ 'blah'. Every place that 'z' is used, it will be specialized,
+ and the type parameter '@a' will be substituted.
+
+ generic z : @a = blah
+
+ Declares a function f with and without type inference. Both
+ forms are equivalent. 'f' takes two parameters, both of type
+ int, and returns their sum as an int
+
+ const f = {a, b+ var c : int = 42
+ -> a + b + c
+ }
+
+ const f : (a : int, b : int -> int) = {a : int, b : int -> int+ var c : int = 42
+ -> a + b + c
+ }
+
+ 3.2. Literal Values
+
Integers literals are a sequence of digits, beginning with a
digit and possibly separated by underscores. They are of a
generic type, and can be used where any numeric type is
@@ -141,69 +210,57 @@
eg: (1,), (1,'b',"three")
-3. SYNTAX OVERVIEW:
+ 3.3. Control Constructs and Blocks:
+
+ if for
+ while match
+ goto
- Myrddin syntax will likely have a familiar-but-strange taste
- to many people. Many of the concepts and constructions will be
- similar to those present in C, but different.
+ The control statements in Myrddin are similar to those in many other
+ popular languages, and with the exception of 'match', there should
+ be no surprises to a user of any of the Algol derived languages.
+ Where a truth value is required, any type with the builtin trait
+ 'tctest' can be used in all of these.
- 3.1: Declarations:
+ Blocks are the "carriers of code" in Myrddin programs. They consist
+ of series of expressions, typically ending with a ';;', although the
+ function-level block ends at the function's '}', and in if
+ statemments, an 'elif' may terminate a block. They can contain any
+ number of declarations, expressions, control constructs, and empty
+ lines. Every control statement example below will (and, in fact,
+ must) have a block attached to the control statement.
+
+ If statements branch one way or the other depending on the truth
+ value of their argument. The truth statement is separated from the
+ block body
- A declaration consists of a declaration class (ie, one
- of 'const', 'var', or 'generic'), followed by a declaration
- name, optionally followed by a type and assignment. One thing
- you may note is that unlike most other languages, there is no
- special function declaration syntax. Instead, a function is
- declared like any other value: By assigning its name to a
- constant or variable.
+ if true
+ std.put("The program always get here")+ elif elephant != mouse
+ std.put("...eh.")+ else
+ std.put("The program never gets here")+ ;;
- const: Declares a constant value, which may not be
- modified at run time. Constants must have
- initializers defined.
- var: Declares a variable value. This value may be
- assigned to, copied from, and
- generic: Declares a specializable value. This value
- has the same restricitions as a const, but
- taking its address is not defined. The type
- parameters for a generic must be explicitly
- named in the declaration in order for their
- substitution to be allowed.
+ For statements begin with an initializer, followed by a test
+ condition, followed by an increment action. For statements run the
+ initializer once before the loop is run, the test each on each
+ iteration through the loop before the body, and the increment on
+ each iteration after the body. If the loop is broken out of early
+ (for example, by a goto), the final increment will not be run. The
+ syntax is as follows:
- Examples:
+ for init; test; increment
+ blockbody()
+ ;;
- Declare a constant with a value 123. The type is not defined,
- and will be inferred.
+ While loops are equivalent to for loops with empty initializers
+ and increments. They run the test on every iteration of the loop,
+ and
- const x = 123
-
- Declares a variable with no value and no type defined. The
- value can be assigned later (and must be assigned before use),
- and the type will be inferred.
+
+ 3.4. Data Types:
- var y
-
- Declares a generic with type '@a', and assigns it the value
- 'blah'. Every place that 'z' is used, it will be specialized,
- and the type parameter '@a' will be substituted.
-
- generic z : @a = blah
-
- Declares a function f with and without type inference. Both
- forms are equivalent. 'f' takes two parameters, both of type
- int, and returns their sum as an int
-
- const f = {a, b- var c : int = 42
- -> a + b + c
- }
-
- const f : (a : int, b : int -> int) = {a : int, b : int -> int- var c : int = 42
- -> a + b + c
- }
-
- 3.2: Data Types:
-
The language defines a number of built in primitive types. These
are not keywords, and in fact live in a separate namespace from
the variable names. Yes, this does mean that you could, if you want,
@@ -213,7 +270,7 @@
must be explicitly cast if you want to convert, and the casts must
be of compatible types, as will be described later.
- 3.2.1. Primitive types:
+ 3.4.1. Primitive types:
void
bool char
@@ -248,7 +305,7 @@
var y : float32 declare y as a 32 bit float
- 3.2.2. Composite types:
+ 3.4.2. Composite types:
pointer
slice array
@@ -272,7 +329,7 @@
foo[123] type: array of 123 foo
foo[,] type: slice of foo
- 3.2.3. Aggregate types:
+ 3.4.3. Aggregate types:
tuple struct
union
@@ -290,6 +347,8 @@
(a keyword prefixed with a '`' (backtick)) indicating their
current contents, and a type to hold. They are declared by
placing the keyword 'union' before a list of tag-type pairs.
+ They may also omit the type, in which case, the tag is
+ suficient to determine which option was selected.
[int, int, char] a tuple of 2 ints and a char
@@ -304,7 +363,7 @@
;;
- 3.2.4. Magic types:
+ 3.4.4. Magic types:
tyvar typaram
tyname
@@ -333,11 +392,15 @@
@foo creates a type parameter
named '@foo'.
- 3.2.5. Traits:
+ 3.4.5. :
- 3.3: Control Constructs:
- 3.4: Packages and Uses:
- 3.5: Expressions
+ 3.6. Packages and Uses:
+
+ pkg use
+
+ A usefile imports a
+
+ 3.7. Expressions:
4. TYPES:
--
⑨