Module Scalar

module Scalar: sig  end

Functions acting on scalar values: int, string, float, undef, splx, funct, posgbf, gmap, bint etc.

The values in MGS are typed. The universe of types is splitted in two: scalar or atomic values that cannot be decomposed and collections that are aggregate of simpler values. Scalar types includes

• undef this type contains only one value representing an undefinition in various circumstances
• bool the type of the two boolean values true and false
• int the type of signed integers
• bint the type of signed arbitrary-precision integers
• float the type of floating point numbers
• string the type of strings of characters
• symbol the type of symbols, Lisp-like constants definied by a back quoted identifiant (e.g. `Constant)
• funct the type of functions
• posgbf the type of position in a GBF
• splx the type of simplices
• ncell n-dimensionnal cells that are the type of position in a qmf
• gmap the underlying space of a qmf

See : For functionnal values refer also to the chapter Functional.
See : For functions related to simplex, cf. the chapter Chain.
See : For functions related to posgbf, cf. the chapter GBF.
See : For various mathematical constants and arithmetics operators, cf. the chapter Math.

 'acell : any -> bool

Returns true if the argument is a acell and false for any other value.

acell is also the type of the abstract topological cells.

 'string2undef : string -> undef

Returns an undef value with its string argument as a comment
Example :'string2undef("toto") return <undef: toto>

 'undef2string : undef -> string

Returns the comment of an undef value as a string
Example :'undef2string(<undef: toto>) return "toto"

 'val2bool : any -> bool

Convert a value to a boolean.

Any MGS value can be converted into a boolean. This conversion occurs implicitly for instance in the condition of a if ... then ... else ... fi expression. This conversion can be done explicitly using the function val2bool. The conversion rules are the following:

• a undef is converted into false.
• a funct is converted into false.
• a symbol is converted into false.
• an int is converted into true if it is non-zero.
• an bint is converted into true if it is non-zero.
• a float is converted into true if it is different from 0.0.
• a string is converted into true if its length is different from 0.
• a posgbf is converted into true unless it represents the identity element of the group law
• a splx is converted into true if its dimension is different from 0.
• a ncell is converted into true if its dimension is different from 0.
• a gmap XXXXXXX is converted into ????.
• a collection is converted into true only if it is non-empty. Alternatively, a en empty collection corresponds to a false value.

 'not : any -> bool

any_bool

returns the negation of the boolean value associated to its argument. For example not(3) == false.

 and_and : any -> any -> bool

returns the logical conjunction of the two arguments.

The arguments can be any MGS value. See the function 'val2bool for the boolean interpretation of a value. && can be aslo written &.

The evaluation is lazy:

false && (?("Hello"); true)

does not print Hello to the terminal.

Warning: a && b is not an ordinary function call but a special form that is expansed during the parsing to if a then b else false fi. The quoted name does not exist.

 || : any -> any -> bool

returns the logical disjunction of the two arguments.

The arguments can be any MGS value. See the function 'val2bool for the boolean interpretation of a value.

The evaluation is lazy:

true || (?("Hello"); true)

does not print Hello to the terminal.

Warning a || b is not an ordinary function call but a special form that is expansed during the parsing to if a then true else b fi. The quoted name does not exist.

 'string_length : string -> int

Returns the length of it's string argument

 'string_get : string -> int -> string

string_get(s, n) returns character number n in string s. The first character is character number 0. The last character is character number string_length(s) - 1. Returns <undef> if n is outside the range 0 to string_length(s) - 1.

 'string_make : int -> string -> string

string_make(n, c) returns a fresh string of length n, filled with the first character of string c. Returns <undef> if n is negative or too big (currently, too big means greater than 16777211 characters).

 'string_sub : string -> int -> int -> string

string_sub(s, start, len) returns a fresh string of length len, containing the characters number start to start + len - 1 of string s. Returns <undef> if start and len do not designate a valid substring of s; that is, if start < 0, or len < 0, or start + len > string_length s.

 'string_index : string -> string -> int

string_index(s, c) returns the position of the leftmost occurrence in string s of the first character of string c. Returns <undef> if c does not occur in s.

 'string_rindex : string -> string -> int

string_rindex(s, c) returns the position of the rightmost occurrence in string s of the first character of string c. Returns <undef> if c does not occur in s.

 'string_index_from : string -> int -> string -> int

Same as string_index, but start searching at the character position given as second argument. string_index(s, c) is equivalent to string_index_from(s, 0, c).

 'string_rindex_from : string -> int -> string -> int

Same as string_rindex, but start searching at the character position given as second argument. string_rindex(s, c) is equivalent to string_rindex_from(s, string_length(s) - 1, c).

 'string_contains : string -> string -> bool

string_contains(s, c) tests if the first character of c appears in the string s.

 'string_contains_from : string -> int -> string -> bool

string_contains_from(s, start, c) tests if the first character of c appears in the substring of s starting from start to the end of s. Returns <undef> if start is not a valid index of s.

 'string_rcontains_from : string -> int -> string -> bool

string_rcontains_from(s, start, c) tests if the first character of c appears in the substring of s starting from the beginning of s to index stop. Returns <undef> if start is not a valid index of s.

 'gensym : symbol -> symbol

string -> symbol

gensym(s) generates a symbol from the string or the symbol s. When s is a string, unless the first character of s is a back quote, gensym(s) adds a back quote at the beginning of s:

gensym("foo")

returns

`foo1

and

gensym("`foo")

returns

`foo2

Obviously,

gensym(`foo)

returns

`foo3

The uniqueness is given by an integer that is concatenated at the end of the argument and incremented. gensym dosen't check if this integer is incremented out of range.

 'ncell : any -> bool

Returns true if the argument is a ncell and false for any other value.

ncell is also the type of the QMF topological cells.

 'gmap : any -> bool

Returns true if the argument is a gamap and false for any other value.

gmap is also the type of the Generalized Maps containing the QMF topological cells.

 'posgbf : any -> bool

Returns true if the argument is a posgbf and false for any other value.

posgbf is also the type of the simplex.